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BERG'S 




COMPLETE 




TIMBER TEST 




RECORD. 

FOR 




ENGINEERS, ARCHITECTS, 




INSPECTORS OF WOOD IN CONSTRUCTION, 




CONTRACTORS, BRIDGE MEN, ETC- 


T A 

$49 


CHICAGO 

B. S. WASSON &c CO. 

91-93 s. Jefferson St. 

[Copyright, 1899. All rights reserved.] 












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PREFACE. 



The only Complete Compilation of Timber Tests, containing 
the recommendations made by leading authorities during the last 
twenty-five years, and the United States Forestry Division Re- 
ports and Tables, were recently published in our new book 
American Railway Bridges and Buildings," and the reports have 
been in such frequent demand by others outside of the railway 
service that we herewith republish, in convenient form, the entire 
matter relating to timber tests. 

The work is especially designed to meet the needs of Engi- 
neers Architects, Inspectors of wood in construction, Contract- 
ors Bridge men, etc., and will without doubt by them be appre- 
ciated and of great value. As it has been adopted by the principal 
Colleges of Civil Engineering, as a Reference and Text its im- 
portance and value to practical men is. greatly emphasized ' 

it may be well to state that the Government Reports, pub- 
lished officially by the Government, were in such demand that the 
volume in which they were published was soon exhausted These 
Keports are now herewith preserved for general distribution 

In reproducing the Reports we did not deem it necessary to 
alter the electrotype plates of our original work, from which this 
pamphlet ,s printed, and the reader will observe that the pajre 
number is the same as appears in the original work where the 
matter was first produced. B . S. WASSON & CO 



BERG'S COMPLETE 

TIMBER TEST RECORD 



INCLUDING THE UNITED STATES FORESTRY DI- 
VISION REPORTS AND TABLES GIVING ULTI- 
MATE BREAKING STRENGTH OF AMERICAN 
TIMBERS, ORIGINALLY PUBLISHED IN OF- 
FICIAL FORM BY THE GOVERNMENT, BUT NOW 
ENTIRELY EXHAUSTED, AND ONLY FOUND 
AND PRESERVED FOR GENERAL DISTRIBUTION 
IN THIS PUBLICATION. 



REPORT: STRENGTH OF BRIDGE AND TRESTLE 

TIMBERS. * 

Your committee appointed to report on "Strength of Bridge 
and Trestle Timbers, with special reference to Southern Yellow 
Pine, White Pine, Fir, and Oak," desire to present herewith, as 
part of their report, the very valuable data compiled by the chair- 
man of the committee, relative to tests of the principal American 
bridge and trestle timbers and the recommendations of the leading 
authorities on the subject of strength of timber during the last 
twenty-five years, embodied in the appendix to this report and 
tabulated for easy reference in the accompanying tables I. to IV. 



*Reports presented at Fifth Annual Convention, held at New Orleans, 
La., October, 1895. 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 221 

t The uncertainty of our knowledge relative to the strength of 
timber is clearly demonstrated after a perusal of this information 
and emphasizes, better than long dissertations on the subject the 
necessity for more extensive, thorough, and reliable series of tests 
conducted on a truly scientific basis, approximating, as nearly as 
possible, actual conditions encountered in practice. 

The wide range of values recommended by the various rec- 
ognized authorities is to be regretted, especially so when undue 
influence has been attributed by them in their deductions to 
isolated tests of small size specimens, not only limited in number 
put especially defective in not having noted and recorded properly 
the exact species of each specimen tested, its origin, condition, 
quality, degree of seasoning, method of testing, etc. 

The fact has been proved beyond dispute that small size speci- 
men tests give much larger average results than full size tests 
owing to the greater freedom of small selected tests pieces from 
blemishes and imperfections and their being, as a rule, compara- 
tively drier and better seasoned than full size sticks The exact 
increase, as shown by tests and by statements of different authori- 
ties, is from ten to over one hundred per cent. 

Great credit is due to such investigators and experimenters as 
Professors G Lanza, J. B. Johnson, H. T. Bovev, C. B Wins" 
and Messrs. Onward Bates, W. H. Finlev, C. B. Talbot and 
ethers, ior their experimental work and agitation in favor of full 
size tests. Professors G. Lanza, R. H. Thurston, and William H 
Burr have contributed valuable treatises on the subject of strength 
ot timber. The extensive series of small and full size United Stales 
Government tests conducted in 1880 to 1882, at the Watertown 
arsenal, under Col. T. T. S. Laidley, and more recentlv the very 
elaborate and thorough timber tests being conducted by the 
United States Forestry Division under Dr. B. E. Fernow chief 
and Professor J. B. Johnson, of Washington University, St Louis' 
aftord us to-day, in connection with the work of the above men- 
tioned experimenters, our most reliable data from a practical 
standpoint. F A ^uicdi 

The test data at hand and the summary criticisms of leading 
authorities seem to indicate the general correctness of the follow 
ing conclusions: 

1. Of all structural materials used for bridges and trestles 
timber is the most variable as to the properties and strength of dif- 
terent pieces classed as belonging to the same species, hence im- 
possible to establish close and reliable limits of strength for each 
species. fe 

,.„ 2 - The various names applied to one and the same species in 
different. parts of the country lead to great confusionTcSng 
or applying results of tests. y & 



222 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

3. Variations in strength are generally directly proportional 
to the density or weight of timber. 

4. As a rule, a reduction of moisture is accompanied by an 
increase in strength; in other words, seasoned lumber is stronger 
than green lumber. 

5. Structures should be in general designed for the strength 
of green or moderately seasoned lumber of average quality and not 
for a high grade of well-seasoned material. 

6. Age or use do not destroy the strength of timber, unless 
decay or season-checking takes place. 

7. Timber, unlike materials of a more homogeneous nature, 
as iron and steel, has no well defined limit of elasticity. As a rule, 
it can be strained very near to the breaking point without serious 
injury, which accounts for the continuous use of many timber 
structures with the material strained far beyond the usually ac- 
cepted safe limits. On the other hand, sudden and frequently in- 
explicable failures of individual sticks at very low limits are liable 
to occur. 

8. Knots, even when sound and tight, are one of the most 
objectionable features of timber, both for beams and struts. The 
full size tests of every experimenter have demonstrated, not only 
that beams break at knots, but that invariably timber struts will 
fail at a knot or owing to the proximity of a knot, by reducing the 
effective area of the stick and causing curly and cross-grained 
fibers, thus exploding the old practical view that sound and tight 
knots are not detrimental to timber in compression. 

9. Excepting in top logs of a tree or very small and young 
timber, the heart-wood is, as a rule, not as strong as the material 
farther away from the heart. This becomes more generally ap- 
parent, in practice, in large sticks with considerable heart-wood 
cut from old trees in which the heart has begun to decay or been 
wind-shaken. Beams cut from such material frequently season- 
check along middle of beam and fail by longitudinal shearing. 

10. Top logs are not as strong as butt logs, provided the latter 
have sound timber. 

11. The results of compression tests are more uniform and 
vary less for one species of timber than any other kind of test; 
hence, if only one kind of test can be made, it would seem that a 
compressive test will furnish the most reliable comparative results. 

^ 12. Long limber columns generally fail by lateral deflection 
or "buckling" when the length exceeds the least cross-sectional 
dimension of the stick by twenty, in other words, the column is 
longer than twenty diameters. In practice the unit stress for all 
columns over fifteen diameters should be reduced in accordance 
with the various rules and formulae established for long columns. 
13. Uneven end-bearings and eccentric loading of columns 
produce more serious disturbances than usually assumed. 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 223 

14. The tests of full-size, long, compound columns, com- 
posed of several sticks bolted and. fastened together at intervals, 
show essentially the same ultimate unit resistance for the com- 
pound column as each component stick would have if considered 
as a column by itself. 

15. More attention should be given in practice to the proper 
proportioning of bearing areas; in other w r ords, the compressive 
bearing resistance of timber with and across grain, especially the 
latter, owing to the tendency of an excessive crushing stress across 
grain to indent the timber, thereby destroying the fiber and in- 
creasing the liability to speedy decay, especially w T hen exposed to 
the weather and the continual working produced by moving loads. 

The aim of your committee has been to examine the con- 
flicting test data at hand, attributing the proper degree of im- 
portance to the various results and recommendations, and then 
to establish a set of units that can be accepted as fair average 
values, as far as known to-day, for the ordinary quality of each 
species of timber and corresponding to the usual conditions and 
sizes of timbers encountered in practice. The difficulties of exe- 
cuting such a task successfully cannot be overrated, owing to ihe 
meagerness and frequently the indefiniteness of the available test 
data, and especially the great range of physical properties in dif- 
ferent sticks of the same general species, ' not only due to the 
locality where it is grown, but also to the condition of the timber 
as regards the percentage of moisture, degree of seasoning, phys- 
ical characteristics, grain, texture, proportion of hare and soft 
fibers, presence of knots, etc., all of which affect the question of 
strength. . 

Your committee recommends, upon the basis of the test data 
at hand at the present time, the average units for the ultimate 
breaking stresses of the principal timbers used in bridge and trestle 
constructions shown in the accompanying table. 

In addition to the units given in the table, attention should be 
called to the latest formulae for long timber columns, mentioned 
more particularly in the Appendix to this report, which formulae 
are based upon the results of the more recent full-size timber 
column tests, and hence should be considered more valuable than 
the older formulae derived from a limited number of small-size 
tests. These new formulae are Professor Burr's App. I.; Professor 
Ely's, App. J. ; Professor Stanwood's, App. K. ; and A. L. John- 
son's App. V. ; while C. Shaler Smith's formulae will be better un- 
derstood after examining the explanatory notes contained in 
App. L. 

Attention should also be called to the necessity of examining 
the resistance of a beam to longitudinal shearing along the neutral 
axis, as beams under transverse loading frequently fail by longi- 
tudinal shearing in place of transverse rupture. 



T224 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

In addition to the ultimate breaking unit stress the -designer 
of a timber structure has to establish the safe allowable unit stress 
for the species of timber to be used. This will vary for each par- 
ticular class of structures and individual conditions. The selec- 
tion of the proper "factor of safety" is largely a question of per- 
sonal judgment and experience, and offers the best opportunity 
for the display of analytical and practical ability on the part of the 
designer. It is difficult to give specific rules. The following are 
some of the controlling questions to be considered: 

The class of structure, whether temporary or permanent, and 
the nature of the loading, whether dead or live. If live, then 
whether the application of the load is accompanied by severe 
dynamic shocks and pounding of the structure. Whether the as- 
sumed loading for calculations is the absolute maximum rarely to 
be applied in practice, or a possibility that may frequently take 
place. Prolonged heavy, steady loading, and also alternate tensile 
and compressive stresses in the same piece, will call fo,r lower aver- 
ages. Information as to whether the assumed breaking stresses 
are based on full-size or small-size tests, or only on interpolated 
values averaged from tests of similar species of timber, is valuable, 
in order to attribute the proper degree of importance to recom- 
dended average values. The class of timber to be used, and its 
condition and quality. Finally, the particular kind of strain the 
stick is to be subjected to, and its position in the structure with 
regard to its importance and the possible damage that might be 
caused by its failure. 

In order to present something definite on this subject, your 
committee presents the accompanying table, showing the average 
safe allowable working unit stresses for the principal bridge and 
trestle timbers, prepared to meet the average conditions existing 
in railroad timber structures, the units being based upon the ulti- 
mate breaking unit stresses recommended by your committee and 
the following factors of safety, viz. : 

Tension, with and across grain 10 

Compression, with grain 5 

Compression, across grain 4 

Transverse, extreme fiber stress 6 

Transverse, modulus of elasticity 2 

Shearing, with and across grain 4 

In conclusion, your committee desires to emphasize the im- 
portance and great value to the railroad companies of the country 
of the experimental work on the strength of American timbers 
being conducted by the Forestry Division of the United States 
Department of Agriculture, and to suggest that the American As- 
sociation of Railway Superintendents of Bridges and Buildings en- 
dorse this view by official action, and lend its aid in every way possi- 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 225 

bfe to encourage the vigorous continuance of this series of govern- 
ment tests, which bids fair to become the most reliable and useful 
vork on the subject of strength of American timbers ever under- 
taken. With additional and reliable information on this subject, 
far-reaching economies in the designing of timber structures can 
be introduced, resulting not only in a great pecuniary saving to the 
railroad companies, but also offering a partial check to the enor- 
mous consumption of timber and the gradual diminution of our 
structural timber supply. 

WALTER G. BERG, Chairman, Lehigh Valley Ry., 
J. H. CUMMIN, Long Island Ry., 
JOHN FOREMAN, Phil. & Reading Ry., 

H. L. FRY, C, F. & Y. V. Ry., 

Committee. 



226 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 






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228 AMERICAN RAILWAY BRIDGES AND BUILDINGS 

STRENGTH OF BRIDGE 
TABLE 1 — 

ULTIMATE BREAKING STRESS, IN 
Compiled for the Fifth Annual Convention of the Association of 



AUTHORITY 






DESCRIPTION. 



Tension. 



With Grain. 



Limits. 



Av 



Across 
Grain. 



Lim. Av 



W. J. M. Rankine 
Chas. H. Haswell. 



John C. Trautwine. . 
Robert H. Thurston 
Louis DcC.Berg 



F.E. Kiauer 

Malverd A. Howe .. 

William Kent. ... 
A. L.Johnson 



A 
A 

A 
W 



Red oak.# 

English oak 

Oak 

White oak » — 

Live oak 

Canadian white oak 

Red oak •• 

Pennsylvania oak, seasoned 



10,000-19,800 



10,250 



16,500 
16,380 



Oak. 



White oak 

Live oak « • 

Basket, black, and red oak. 



Oak. 



White oak 

Live oak 

Canadian oak. 

Wbite oak 

Red oak 

Live oak 

Canadian oak. 
White oak — 

White oak 

Live oak 

Oak 

White oak . . . 



10/250 
2",333 ' 



10,000 ■ 
10,000 . 
10,000 J. 



10,000 
10,000 



11,000 
8,000 
11,000 
7,500 
16,000 
10,000 
10,000 

i6,oco 



U. S. Ordnance Depar't, 

Capt. T. J. Rodman 

Thomas Laslett. ... 



R. G. Hatfield 



U. S. 10th Census. 



Robert H. Thurston 
St. Louis Bridge.... 



U. S. Ordnance Depar't, 
Watertown Arsenal.... 



B. i. 
B.b. 



.a. 
B.h. 

B.C. 
B.d. 

B.f. 



White oak, well seasoned 

White oak 

Baltimore oak 

Oaks, average 

White oak 

Canadian oak — 

Live oak • 



White oak 

White, post, iron, red. nnd black oak 

Scrub and basket oak 

Chestnut and live oak 

Pin oak 

White oak 

Live oak 

White oak, blocks 

White oak, round columns 

Black oak, blocks 

Black oak, round columns 

White oak 

Red oak ■ 

Yellow oak 



13,333-25,222 



12,670-22,703 

7,600-12,133 

20,200-20,520 



7,021 
3,832 

19,500 



13,210 
10,310 



17,410 
10,124 
20,390 



fflf' 

w 
03 



G.Lanza 

D. Kirkaldy & Son. 



D.c. 
G.a. 
G.a. 
E.b. 



White 
White 
"White 
White 
White 
White 
White 
White 



oak, 36 beams 

oak, 10 posts and blocks 

oak, 18 old posts 

oak, 5 beams, 5 feet span. . . . 
oak, 5 beams, 11 feet span. . . 
oak, 5 posts, about 6 diams.. 
oak, 5 posts, about 11 diams. 
oak, 5 posts, about 23 diams. 



2,300 



2,300 



.2,300 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 229 
AND TRESTLE TIMBERS* 
OAK. 

POUNDS, PER SQUARE INCH. 

Railway Superintendents of Bridges and Buildings, October, 1895, by Walter G. Berg. 



Compression. 



Witn Grain. 



Limits. 



Av. 



Across Grain. 



Limits. 



Inden- 
tation. 



Av. 



Transverse. 



Extreme Fiber 
Stress. 



Limits. 



Av. 



Modulus of Elasticity. 



Limits. 



5,000- 7,000 



5,500- 8,000 
8,000-10,000 



3,150- 7,000 



6,000 
10,000 

'7,566 
6,850 
5,982 



6,000 



Av. 



Shearing. 



With. Grain. 



Limits. 



7,200 
6,000 
6,850 
6,000 

'7,000 
7,000 

4*6661 



2,300 



10,000-13,600 



1-10 in. 
1-10 '• 

|3prct. 



2,400 
4,500 



1.600 
1,600 

1,200 



10,600 



10,800 

11,520 

10,512 

9,720 



AV. 



Across 
Grain. 



Lim. 



10,800 
10,800 
15,300 

1 1,000 
12,000 
10,000 
7,200 
6,500 
7,300 , 
7,000 . 
5,670. 



6,000 



1,200,000-1,750,000 



1,000,000-2,000,000 



974,000-2,283,000 



2,150,000 
1,710,666 



1,500,000 



2,300 
780 



400-700 



900,000 
1,200,000 



1,240,000 
1,500,000 
1,500,000 

1,100,666 



4,691-10,058 

6,531- 9,775 
5,810- 9,070 



8,200- 3,778 
6,000-12,200 

MOO*- 6,980 



6,964 
5,891 

8,000 

11,100 



7,000 
6,000 
7,500 
6,500 
7,140 
10,410 
3,505 
7,812 

6,] 01 
7,192 



1-20 in. 

1-20 " 
1-100 " 
1-10 " 
1-10 " 
1-10 " 
1-10 
1-10 



1,300-2,200 
l,6o6"-2,o66 



1-20 



2,650 

6,800 
1,600 
4,000 
4,000 
4,200 
4,500 
3,000 



780 



800 
750 
700 
&"• 
780 
850 



800 



8,460-17,340 



7,010-18,360 



10,900 

9,800 

8,550 

11,700 

10,600 



1,750 

1,800 

2*856 
.1).. 



879,000-2,103,000 



9,840 
11,280 



1,330,000 
1,770,000 
1,114,560 
1,339,200 
1,929;312 



1,076-1,474 



1,620,000 
1,851,428 



3,132- 4,450 
2,943- 6,147 



3,470 
3,957 



3.285 
3,418 
2.891 



1,250 



842 
803 



3,535- 7,834 



5,863 



6,890 
8,550 



744,774-1,777,500 



1,131,100 



Av. 



"V 



4,000 
4,032 



4,425 
8,480 

4,666 



4,400 

8,566 

4,400 
4,400 



230 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 



STRENGTH OF BRIDGE 
TABLE 2.— 

ULTIMATE BREAKING STRESS, IN 
Compiled for the Fifth Annual Convention of the Association of 



AUTHORITY. 



a © 
© o 

a© 
< 



DESCRIPTION. 



Tension 


. 




With Grain. 


Across 
Grain. 


Limits. 


Av. 


Lim. 


AV. 



« 

O rA 

H 

OS 



Chas. H. Haswell 

John C. Trautwine 

Robert H. Thurston 

Louis DcC. Berg 

F. E. Kidder 

Malverd A. Howe 

H. T. Bovey 

A. L. Johnson 

W. M.Patton ... 

U. S. Ordnance Depar't. 

Capt. T. J. Rodman 

R. G.Hatfield 

U.S. 10th Census 

Robert H. Thurston 

St. Louis Bridge 

F.E. Kidder 

U. S. Ordnance Depar't, 
Watertown Arsenal 

H.T.Bovey 

H. T. Bovey 



U. S. Ordnance Depar't 

Watertown Arsenal . . 

G. Lanza 

Onward Bates 

W. H. Finley 



A 
A 
A 
A 
A 
A 
M 
W 
A 



White pine 

White pine 

White pine 

White pine 

White pine 

White pine 

Canadian (Ottawa) white pine. 

White pine 

White pine 



3,000-7,500 



11,800 
10,000 



9,000 

7,000 

10,000 



7.000 
7,000 



550 
550 



550 



GO 

a 
a 
< . 

CO ^ 

u* a 
xo 

O 
a> 

W 



B. i. 
B. a. 

B.h. 

B.C. 
B.d. 

B.e. 

B. f. 

Q 

M 



White pine, well seasoned. 
White pine 

White pine .. 



White pine 

White pine, blocks.... 

White pine, columns 

White pine » 

White pine , 

White pine, resistance to keys 

tearing out 

Canadian (Ottawa) white pine. 



11,433-11,960 



5,300-11,299 
,- 8,503-14,273 



12,000 



6,880 



8,916 
11,396 



GO 

•J 
& . 

b* °> 






M.i. 
BC.il. 

H.a. 
D.d. 



R.a. 
R.b. 

S 



Canadian (Ottawa) white pine, 

15 beams , 

Canadian (Ottawa) white pine,. 

68 posts 

White pine, posts, under 32 dia. 
White pine, posts 32-62 diams. . . 

White pine, 37 beams 

Western white pine, kiln dried, 

8 beams .- 

White pine, new and old, 30 b'ms 
White pine, new, 14 beams...... 

White pine, 31 years in use, 12 

beams. 

White pine, new, 2 beams 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 231 



AND TRESTLE TIMBERS. 

WHIT.E PINE. 

POUNDS. PER SQUARE INCH. 

Railway Superintendents of Bridges and Buildings, October, 1895, by Walter G. Berg. 



Compression. 


TllANVERSE. 


Shearing. 




With Grain. 


Across Grain. 


Extreme Fiber 

Stress. 


Modulus of Elasticity. 


With 
Grain. 


Across 
Grain. 


Limits. 


Av. 


Lim. 


Inden- 
tation. 


Av. 


Limits. 


Av. 


Limits. 


Av. 


Lim. 


Av. 


Lim. 


Av. 




5,775 
6,000 






550 




9,000 
8,100 




1,600,000 SKfl-snft 


490 






5,000-7,000 
3,000-6,000 










. 


2,480 












1,000,000 

850,000 

1,073,000 

1,750,000 




490 
450 
490 
325 










700 




4,000 
4,320 






2,500 

2,480 
2.48C 


2,800-4,500 








5,400 
5,000 
3,500 
9,500 




1-10 in. 


600 


















3 pr ct. 


440 




4,400 
9,000 




870,000 




300 
482 














2,480 


■ 


J 














SJ01 7-5,775 
5,579-7,502 

3,750-5,600 










6,798-7,092 
















6,650 

5,400 

9,590 
3,261 
3,727 




1-20 in. 

1-100 " 

1-10 " 


800 

600 

1,200 


9,000 
5,280 




1,252,800 


433-530 


480 






5,610-11,530 


868,000-1,478,000 






883,636 










3,083-3,694 
3,580-3,900 


555-722 




611 




































7,578-9,440 


8,297 


1,251,252-1,461,728 


1,388,497 












5,617 




1-20 " 


1,045 




370 
421 






' 










236-611 

273-382 


1 


















































■ 










2,500-4,936 


3,388 


433,250-l,f84,240 


754,265 












3,843 

2,414 
















l,"B87-3,700 
•1;000-2,000 






















































2,456-7,251 


4,451 

5,482 
3,872 
3,694 

7,051 
5,402 


727,200-1,565,000 


1,122,000 

1,183,037 
1,098,000 






























2,350-5,376 
2,160-5,131 

5,139-10,616 


712,500-1,430,900 






























715,000-1,900,000 


1,208,250 
982,500 

















































232 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 



STRENGTH OF BRIDGE 

TABLE 3.— SOUTHERN YELLOW PINE, LONG-LEAF YELLOW 

ULTIMATE BREAKING STRESS, IN 
Compiled for the Fifth Annual Convention of.the Association of Rail- 



AUTHORITY. 



a © 
© © 

aa 
p,© 
< 



DESCRIPTION. 



Tension. 



With Grain. 



Limits. 



Av. 



Across 
Grain. 



Lim. 



AV. 



< 
> 

« 

a 

s 
s 

o 

c 

63 



m 

5 » 
CD e-> 

ID 

s 

p 



W. J, M. Rankine 

ChasH. Haswell 

John C. Trautwine 

Robert H. Thurston 

Lbuis DeC. Berg 

F. E. Kidder 

Malverd A. Howe 

G. Lanza.... 

A.L.Johnson 

W. M. Patton 

U S. Ordnance Depar't, 

Capt. T. J. Rodman 

Thomas Laslett 

R. G.Hatfield '.. 

U. S. 10th Census , . 

Robert H. Thurston 

St Louis Bridge. . . . < 

F.E. Kidder 

U. S. Ordnance Depar't, 

Watertown Arsenal — 
U. S. Forestry Departra't, 

Bulletin No. 8 

U. S. Forestry Departm't, 

Bulletin No. 8...; 

G. Lanza 

U. S. Ordnance Depar't, 
Watertown Arsenal .... 



A 

A 



A 
A 
D.b. 
W 
A 



Yellow pine 

Pitch pine 

Yellow pine 

Virginia pine 

Georgia pine 

Yellow pine 

Georgia yellow pine. . 

Pitch pine .»... 

Yellow pine 

Pitch pine .... ^ ........ . 

Yellow pine 

Georgia yellow pine . . 

Pitch pine 

Yellow pine 

Southern yellow pine. 

Yellow pine 

Long- leaf pine 

Yellow pine. 



5,000-12,000 
8,000-10,000 



13,000 
19,200 



10,000 

io.ooo 



9,000 
12,000 
10.000 
16,000 
10,000 



12,000 
20,700 



B.i. 
B.b. 
B. a. 

B.h. 

B.C. 
B.d. 

B.e. 

B. f. 

Q. 



Yellow pine, well seasoned. 

Pitbh pine. . ..-...» , 

Georgia pine 

Pitch pine , 



Long-leaf Georgia pine 

Yellow pine 

Yellow pine, blocks 

Yellow pine, columns .- 

Yellow pine 

Yellow pine 

Yellow pine, resistance to keys tear'g out 

Long-leaf pine, from Alabama 



12,600-19,200 



12,066-17,922 



4,170-31,890 



4,666 
16,000 



20,700 



15,478 



16,029 



550 
550 
'550 
550 
550 



•J 
fog 

'g; a 

°> u 

&*> 

CO 

w 



C 

D.b. 
G.a. 
H.a. 
H.a. 
H.c. 



Long-leaf pine, from Alabama 

Yellow pine, 61 beams 

Yellow pine, 18 posts and b? ocks 

Yellow pine, posts under 22 diams 

Yellow pine, posts 22 to 62 diams 

Yellow pine, straight grain, well sea- 
soned, 12 posts 

Yellow pine, very slow growth, 3 posts. . . 
Yellow pine, very green and wet, 3 posts. 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 233 



AND TRESTLE TIMBERS. 

PINE, GEORGIA. YELLOW PINE, AND SOUTHERN PITCH PINE. 

POUND8. PER SQUARE INCH. 

way Superintendents of Bridges and Buildings. October, 1895, by Walter G. Berg. 



Compression. 


Transverse. 


— =E=3 

Shearing. 


With Grain. 


Across Grain. 


Extreme Fiber 
Stress. 


Modulus of Elasticity. 


With Grain. 


Across Grain. 


Limits. Av. 


Limits. 


« O 

— — 


Av. 


Limits. 


Av. 


Limits. 


Av. 


Lim, 


Av. 


Lim. 


Av. 




5,400 
8,947 














- 
















550 
550 
550 
550 


. 


9,864 
9,360 




2,430,000 




510 
























8,200 






1 






















14,400 
9,000 

15,300 
9,900 
7,000 
8,000 
6,000 
7,200 
6,600 
6,750 


























1,600,000 






4,340-5,735 














* 








5,735 
























5,053 


6,500.10,000 














1,600,000 
1900,000 

laoo.ooo 

1,200,000 
1,225,000 
1,780,000 
1,600,000 




510 
























5,400 
7,400 
8,900 


















4,800 




_ 




1,850 








500 
510 
510 
325 




5,700 
















5,000 


4,400-6,000 
















5,700 


8,500 




i-lOin 


1,300 
















5,000 

7,750 

15,000 












5,000 
11,500 




3p.c. 


645 






1,440,000 




500 
843 


















5,735 




















7,836-8,350 










8,796-:ll,676 


v 9,972 

11,900 
15.300 
9,792 

16,740 














6,462 
9,500 










1,900,000 
2,468,800 
1,225,152 










8,170-11,503 




l-20in 


2,250 


4,000-21,168 




713-934 


840 










4,010-10,600 


8,500 

11,950 
4,722 
4,735 




1-100 
1-10 M 


1,300 
2,600 


9,220-21,060 


879,000-2,878,000 












3,534,727 










4,500-4,917 
4,650-4,820 


1,000-1,222 




1,092 




































12,280-14,654 


13,048 


1.707,282-1,926,160 


1,821,630 
















1-20" 


1,900 




352 
512 

852 




















337-720 
464-1,299 






4,587-9,850 


7,228 


584-2,094 


15p.c. 


1,517 


. 




' 
































4,268-16,200 
3,963-11,360 


12,250 
7,486 


842,000-3,117,370 
1,162,467-2,386,096 


2,069,650 




















1,757,900 










3,604-5,452 


4,544 
4,442 
















3,430-5,677 
























1,700-3,500 
























5,593-8,644 


7,386 
9.339 
3,015 
























7,820-10,250 
























2,795-3,180 












































I 



c 



234 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

STRENGTH OF BRIDGE 

TABLE 4.— DOUGLAS, OREGON, WASHINGTON, 

ULTIMATE BREAKING STRESS, IN 

Compiled for the Fifth Annual Convention op the Association of Railway Super* 



AUTHORITY 



a© 



DESCRIPTION. 



Tension. 



With Grain. 



Limits. 



Av. 



Across 
Grain*. 



Lim. 



Av. 



H 

is 

B 



Robert H. Thursion 

F. E. Kidder - I 

H.T.Bovey 

Arthur Brown, 

Southern Pacific Ry . . . . 
A. L. Johnson 

U. S. Ordnance Depar't, 
Capt. T. J. Rodman. 

U. S. 10th Census . , . . 

W. B.Wright.. ...... *..., 

Oregon & California R.R. 

Robert H. Thurston 

U. S. Ordnance Depar't* 

Watertown Arsenal..., 

A. T. Bovey 

John D. Isaacs, 
Southern Pacific Ry . . . . 



A 
A 

M 



O.b. 
W 



Oregon pine 

California spruce. 

Oregon pine •. — 

Oregon spruce 

Douglas fir. 

Douglas fir, specially selected . 
Douglas fir, ordinary first qual. 



Pacific Northwest (Douglas) fir 
Douglas fir 



9,000-14,000 
12,000-14,000 



13,800 



15,900 



B 



CO 

< 

I 

ft. 
O 

so 

s 

u 

00 

B 



B. i. 

B.h. 
O.d. 

O.e. 

O.c. 

B.f. 

M. in 
M. iv 



Oregon yellow fir 

Oregon red fir 

Oregon white fir 

Red and yellow Douglas fir 

Red fir 

Yellow fir 



Douglas fir 

Oregon sugar pine. . 

Oregon pine 

California spruce.. . . 

Oregon pine ... 

Oregon spruce 

Douglas fir, 71 tests. 
Douglas fir 



Douglas fir. 



13,633-16,833 



2,485-18,856 



12,867 
14,533 



10,872 
11,550 

16,600 
11,000 



13,810 
16,160 
11,612 



15,900 



B 
B 

N 

*-» 

OQ 

>J 
►J 

» 
fa 

fe 

o 

<n 
H 

a 

p 

CO 

B 

K 



Onward Bates. 



A. T. Bovey 



C. B- Talbot, Northern 
Pacific R. R...* '. 



A. J. Hart, Chic, Mil. & 
St. Paul R.R 



A. J. Hart & C. B. Talbot. 
S. Kedzie Smith, , 



State of Washington 
Chapter, American Inst. 
Architects , 



Charles B. Wing. 



R. c. 

M.i. 

M.i. 

M. ii. 
M.i. 
M.n. 

N.a. 

N.e. 



N.b. 



N.c. 
N.d. 

O.a. 
N.f. 



U 



Douglas fir, 12 beams 

Douglas fir, 10 beams (omitting 
2 bad sticks) i •... 

Douglas fir, specially selected, 

4 beams 

Douglas fir, ordinary first qual- 
ity, 15 beams 

Douglas fir, 122 posts 

British Colum. spruce, 3 beams 
British Colum. spruce, 69 posts 
Wash'n yel. fir, 5 small beams. 

Washington fir, hard, fine grain, 

1 small beam. 

Washington pine, fine grain, 1 

small beam 

Washington yellow fir, green, 

4 beams 

Washington yellow fir, 6 years 

seasoned, 2 beams 

Washington fir, 9 beams 

Washington yellow fir,- close 
grain, 2 beams '. 

Washington red fir, 8 beams. . . . 

Washington yellow and red fir, 
19 beams 



Douglas fir, 11 beams 

Washington yel. fir, 13 beams . 
Washington red fir, 11 beams . 

Average of all tests 

Douglas fir, ordinary No. l, 

merchantable, 10 beams 

Douglas fir, ordinary No. 1, 

Merchantable, 10 small beams 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS, 235 



AND TRESTLE TIMBERS. 

AND CALIFORNIA FIR, PINE, AND SPRUCE 

POUNDS, PER SQUARE INCH. 

intendents of Bridges and Buildings, October, 1895, by Walter G. Berg 





Compression. 






Transverse. 


Shearing. 


With grain. 


Across Grain. 


Extreme Fibei 
Stress. 


Modulus of Elasticity. 


With 
Grain. 


Acrosa 
Grain. 


Limits. 


Av. 

1 


a 

a ® ° 
S *c*f3 

1— 1 ; h* +-> 


AV 


Limits. 


Av. 


Limits. 


Av. 


Lim. 


Av 


. Lim 


. Av. 


9,200-1 1,5C 
9,200-12,80 






. 6,000 

■ 6,000 
■| 4,400 




. .... 




• 11,07 
. 12,22 

. 9,00( 
6,00( 

13,63( 
6,60( 


1 

5 

j...^...'.. ....... 

) 

) 


2,bbb,6cK 

1,430,00( 

1,272,00( 
1,380,00( 


) 


. 84( 
. 31( 

40( 
60C 


) 

) 

) 







• • 3perct. 


50( 












1 


1 












7,488-9,21' 
4,880-9,80( 


* 

7,083 
6,644 


-. ... 





7,740-10,94< 
8,220-17,92C 


1 

6,72* 

4,194 



15,894 
15,030 

8,658 
8,370 

11,071 
12,228 

17,223 


. 

I,308,000r2,579,000 
, 





515-833 


• • » • 

689 





.... 




6,099 
6,132 

3,085 
3,391 





8,597 . 
5,772 . 

6.000 . 


• 2-100 in. 
. 4-100 " 

. 1-20 « 

• 1-20 " 


1,000 
1,000 

1,150 
695 

.# . .. 







.... 


9,200-11,500 
9,200-12,800 





• *»*. *•«•••• ...... 


.... 





786 
311 

*403 

600 





.... 








........... 


1,272,000 


377^411 





.... 

























3,597-7,544 
5,268-7,544 
8,020-10,441 
4,027-3,382 
4,614^5,908 
6,890-9,720 


5,791 
6,214 

9,054 
6,081 
5,i20 

7,847 
9,720 
5,116 

7,323 

6,020 
6,273 

7,830 
5,186 . 

5,420 . 
5,979 . 
7,402 . 
5,186 . 
6,359 . 






— 




























....... 








1,934,500-2,178,100 

926,500-1,770,563 

i,Oll,450Kl',528^99 


2,036,529 
1,431,209 
1,203,633 





















.... 







'. 


5,974 . 
3,617 ! 







.... 














































6,143-7,982 

5,935-6,088 
5,263-7,561 

7,500-8,160 
4,255-6,138 

3,530-8,160 

5,580-7,951 
1,438-12,056 






















































• ItltliMii, , 





********** • 

















... 


















. 





236 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

APPENDIX A. 

EXPLANATORY OF TABLES, SHOWING STRENGTH OF 
BRIDGE AND TRESTLE TIMBERS. TABLES i TO 4. 

These tables were compiled to show all the information avail- 
able in regard to the strength of the principal American bridge and 
trestle timbers. The literature consulted covers the period since 
1875 to date, and the endeavor has been to take into consideration 
£•.11 important test results or recommendations of eminent engineer- 
ing authorities during that time. 

Unless otherwise stated, the timbers mentioned are invariably 
to be considered as American. Considerable trouble is caused in 
a compilation of this kind to classify the results properly, owing 
to the different and also the indefinite names used by the various 
authors and engineers in describing the species of wood tested or 
referred to. 

The explanatory data for the small-size tests, mentioned in the 
tables, are recorded in Appendix "B," while the full-size and very 
valuable tests are given in considerable detail in special articles 
under various headings of the Appendix. 

The average values for strength of timbers recommended by 
different authorities, as given in the tables, are of interest as show- 
ing the results of the studies and researches of these parties. While 
a great many of the unit values given are merely the work of com- 
pilation from the best available data and in many cases clearly 
copied from previous publications, still a great many of the results 
.are from individual experience or unpublished tests. At any rate, 
each author has carefully sifted the information at his command, 
correcting and adjusting it according to his best ability. 

Below will be found a few notes in regard to the professional 
standing of the authors consulted. 

Prof. W. J. M. Rankine, the celebrated English engineering 
authority and experimenter on strength of timber, author of 'Ap- 
plied Mechanics," "Manual of Engineering," etc. 

Prof. Robert H. Thurston, Cornell University, Ithaca, N. Y. 
(formerly Stevens Institute of Technology, Hoboken, N. J.), au- 
thor of "Materials of Engineering," "Materials of Construction," 
and numerous technical books; writer and experimenter on 
strength of timber. 

John C. Trautwine, civil engineer, author of "Trautwine's 
Civil Engineer's Pocket-Book;" writer and experimenter on 
strength of timber. 

F. E. Kidder, civil engineer and architect, Denver, Col., 
author of "Kidder's Architects and Builders' Pocket-Book;" 
writer and experimenter on strength of timber. 

Louis De C. Berg, architect. New York City, member Ameri- 
can Society Civil Engineers, author of "Safe Building." 



STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 237 

A. L. Johnson, civil engineer, in charge of U. S. Forestry Di- 
vision physical timber tests under the direction of Prof. J. B. John- 
son, Washington University, St. Louis, Mo. 

Prof. Malverd A. Howe, Rose Polytechnic Institute, Terre 
Haute, Ind. 

Prof. Gaetano Lanza, Massachusetts Institute of Technology, 
Boston, Mass., well-known writer and experimenter on the 
strength of timber, author of "Applied Mechanics." 

William Kent, mechanical engineer, New York City, author 
of ''Kent's Mechanical Engineer's Pocket-Book," associate editor 
of Engineering News'; well known writer and compiler of experi- 
mental statistics. 

Prof. Wm. H. Burr, Columbia College, New York City, 
author of "The Elasticity and Resistance of the Materials of Engi- 
neering." 

R. G. Hatfield, architect, New York City, author of "Trans- 
verse Strains" (1877), an d "American House Carpenter;" experi- 
menter on strength of timber. 

Thomas Laslett, English writer and experimenter on strength 
of timber, author of "Timber and Timber Trees" (1875). 

Col. T. T. S. Laidley, in charge U; S. Ordnance Department 
timber tests, Watertown arsenal, 1880 and 1881, (Ex. Doc. Xo. 12, 
47th Congress, 1st session, and Ex. Doc. No. i, 47th Congress, 
26. sesrion). 

CapL T. J. Rodman, in charge U. S. Army Department tim- 
ber tests, published in the "Ordnance Manual." 

T. P. Sharpies, in charge of American timber tests for tenth 
census, 1880, published in Vol. IX., on the "Forests of North 
America;" also in tests of materials, U. S. Ordnance Department, 
1883, Ex. Doc. Xo. 5, 48th Congress, 1st session, summary, page 
568. 

Prof. Henry T. Bovey, McGill University, Montreal, Canada, 
writer and experimenter on strength of Canadian timbers. 

Charles H. Haswell, author of Haswell's "Mechanics and En- 
gineers' Pocket-Book." 

W. M. Patton, professor of civil engineering in Virginia, and 
author of a "Treatise on Civil Engineering." 



Continuation of the Appendix to the report on Strength of 
Bridge and Trestle Timbers is printed seperately in back of book 
where the detailed results of various valuable series of timber tests 
are treated under the following heads: 
Appendix B — Record of Timber Tests, with Small Specimens. 
Appendix C — U. S. Forestry Division Tests of Long-leaf Pine, Including 
Tables of "Range of Mechanical Properties of Long-leaf 



238 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

Pine," "Notes and Characteristics of Southern Timber 

Pines." 
Appendix D — Professor Lanza's Full-sized Transverse Tests. 
Appendix E — Miscellaneous Full-sized Tests. 
Appendix F — Longitudinal Shearing Under Transverse Strain. 
Appendix G — Professor Lanza's Full-sized Tests of Timber Columns. 
Appendix H — U. S. Government Full-sized Tests of Timber Columns. 
Appendix I — Professor Burr's Formulas for Timber Columns. 
Appendix J — Professor Ely's Formulas for Timber Columns. 
Appendix K — Professor Stanwood's Formulas for Timber Columns. 
Appendix L — C. Shaler Smith's Formulas for Timber Columns. 
Appendix M — Professor Bovey's Full-sized Tests of Canadian Douglas 

Fir, Red Pine, White Pine, and Spruce. 
Appendix N — Report of Washington State Chapter, American Institute 

of Architects, on Strength of State of Washington Timbers. 
Appendix O — Miscellaneous Tests of the Northwest and Pacific Coast 

Timbers. 
Appendix P — Professor Soule's Tests of California Redwood. 
Appendix Q — United States Government Watertown Arsenal Tests of the 

Shearing Strength of Timber with the Grain Resisting the 

Pulling Out of Pins and Keys. 
Appendix R — Transverse Tests of Full-sized Old and New Bridge 

Stringers Made for the Chicago Milwaukee and St. Paul 

Railway, Under the Direction of Mr. Onward Bates. 
Appendix S — Comparative Transverse Tests of Full-size Old and New 

White Pine Bridge Stringers, Made by Mr. W. H. Finley, 

for the Chicago and Northwestern Railway. 
Appendix T— Tests of Douglas Fir and California Redwood, Made for the 

Southern Pacific Railway by Mr. John D. Isaacs. 
Appendix U— Professor Wing's Full-size Transverse Tests of Douglas 

Fir. 
Appendix V— Mr. A. L. Johnson's Formula for Timber Columns. 
Appendix W— Mr. A. L. Johnson's Recommendations for Unit Values. 
Also diagram of ultimate breaking weight of yellow pine columns and 

other valuable notes and information. 



APPENDIX TO REPORT ON 

STRENGTH OF BRIDGE AND TRESTLE TIMBERS. 

(Continued from page 237.) 

APPENDIX B. 

RECORD OF TIMBER TESTS WITH SMALL SPECIMENS. 

(a) Hatfield's tests ("Transverse Strains," 1877) have been widely quot- 
ed and utilized. Unfortunately the tests were all made on unusually 
small specimens, and hence much higher results than corresponding 
full-size tests show. 

Tensile tests, specimens about one-third inch in diameter. 
Compressive tests, nine tests of each kind of timber, specimens one to 

two diameters high. 
Shearing tests, nine tests of each kind of timber, specimens small. 
Transverse tests, specimens one inch square, short spans. 

(b) Laslett'-s tests of English and foreign timbers ("Timber and Timber 
Trees," 1875; revised edition, 1894). 

Tensile tests, specimens two inches square. 
Compressive tests, small cubes one to four inches in size. 
Transverse tests, specimens two inches square and six feet span. 

(c) Professor Thurston's small-size tests (Journal Franklin Institute, 
October, 1879, and September, 1880). 

Tensile tests, specimens one-half inch in diameter. 

Compressive tests, specimens about one and one-eighth inches in diame- 
ter and two and one-fourth inches long. 

Transverse tests, specimens three inches square and four and one-half 
feet span. 

(d) St. Louis bridge tests made during construction of bridge. All tim- 
ber well-seasoned excepting the white oak. 

Compressive tests on blocks with and across grain, cubes three to six 
inches in size, two to four tests of each kind. Compressive tests on 
round columns, about two and one-fourth inches in diameter, and 
from two to twenty-four inches long; as a rule, length about thirteen 
inches or six diameters; none of the columns over eleven diameters. 

(e) F. E. Kidder's small-size transverse tests (Van Nostrand's Maga- 
zine, February, 1880); five yellow pine specimens, about one and one- 
fourth inch square, and eight white pine specimens, about one and 
one-half inch square, all on supports forty inches apart. Very well 
seasoned timber of excellent quality. 

(f) U. S. Ordnance Department small-size tests, Watertown arsenal, 
Col. T. T. S. Laidley. 

Tensile tests, specimens generally about one inch in diameter. 
Compressive tests with and across grain, specimens small size. 
Compression across grain taken as the force producing an indentation 

of one-twentieth inch. 
Transverse tests, well-seasoned sticks, from one and one-fourth inch to 

four inches square, and spans of twenty-two to forty-four inches. 
Shearing tests, small specimens. 



TIMBER TESTS. 671 

(g) John C. Trautwine, some small-size tests for shearing across grain 
(Journal of the Franklin Institute, February, 1880), valuable as rep- 
resenting shearing values for small, round, wooden tree nails and 
pins. 

These shearing tests, specimens five-eighths inch round, gave the fol- 
lowing values for the ultimate breaking, shearing stress across grain 
in pounds per square inch: 

Ash 6.280 Locust 7,176 

Beech 5,223 Maple 6,355 

Birch = 5.595 "White oak 4,425 

White cedar 1,372 to 1.519 Live oak 8,480 

Central American cedar 3.410 White pine 2,480 

Cherry ....." 2,945 Northern yellow pine 4,340 

Chestnut 1,535 Southern yellow pine 5,735 

Dogwood 6,510 Yellow pine, very resinous. . . .5,053 

Ebony 7,750 Poplar 4,418 

Gum 5,890 Spruce 3,255 

Hemlock 2,750 Black walnut 4,728 

Hickory 6,045 to 7,285 Common walnut 2,830 

(h) U. S. Tenth Census Report, small-size tests of T. P. Sharpies. A 
very large number of American woods, 412 species, were tested in 
over 1,200 specimens. This series of tests is the most comprehen- 
sive, as regards the number of species, ever undertaken, but the re- 
sults are more of comparative than practical value, as the number 
of specimens for each kind was very small and the specimens, as a 
rule, only 1 57-100 inches square in size. The pieces for transverse 
tests were a little over three feet long, and those for compressive 
tests with the grain 12.6 inches long. Results for ultimate compres- 
sion across grain were recorded for a pressure producing an indenta- 
tion of 1-100 inch to 1-5 inch. 

(i) U. S. Army tests by Captain Rodman (Ordnanc, Manual) were made 
over twenty-five years ago on small specimens, although larger than 
other earlier experiments. The pieces for transverse tests were 
about three inches by six inches, and five feet span. 

(j) Professor Thurston, i>r U. S. Geological Survey, 1880, forty small- 
size tests of Oregon pine and California spruce. 

APPENDIX C. 

U. S. FORESTRY DIVISION TESTS OF LONG-LEAF PINE. 

The United Sta es Agricultural Department, under the supervision 
of Dr. B. E. Fernow, Chief of Division of Forestry, has in progress the 
most thorough examination of timber physics on a large scale, based 
on truly scientific principles, ever undertaken in this country. The 
methods In use and the results were published in detail, during 1892 
and 1893, in "Timber Physics," Parts I and II, Bulletins No. 6 and 8, 
Forestry Division, U. S. Department of Agriculture, since which time 
the work has been delayed owing to insufficient appropriations bv Con- 
gress, although It is expected that Part III, giving the researches for 
the four important species of Yellow Pine, will be published the latter 
part of 1895. 

The material examined up to 1893 was exclus'-ely "Long-Leaf Pin*" 
(Pinus palustris), cut from twenty-six specially selected trees from rour 
different sites in Alabama. The range of the results of over two thou- 



672 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 



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sand mechanical tests, conducted by Prof. J. B. Johnson, at Washington 

University, St. Louis, Mo., on large and small specimens, is shown in the 

table herewith, the results having been reduced to the uniform basis of 

15 per cent, moisture. 

The following is offered in explanation of these tests: 

Transverse Tests.— The full-size tests were made on a machine of 

100,000 lbs. capacity, and the small-size tests on a machine capable of 

breaking a 4-inch square stick 6 feet long. 

The ultimate extreme fiber stress is computed from the well-known 

formula,— 

3W1 
f= 

2bh 2 
where f =stress on extreme fiber in lbs. per square inch. 
W=load at center of beam in lbs. 
l=length of beam between supports in inches. 
b=breadth of beam in inches. 
h= height of beam in inches. 

The results of each test were plotted as rectangular co-ordinates, 
using the loads as ordinates and the corresponding deflections as abscis- 
sas. The so-called elastic limit is determined from this curve by the ar- 
bitrary rule locating it at that point of the curve where the rate of de- 
flection is 50 per cent, more than it is at first, it having been found that 
this rule usually places the elastic limit at the point where the deflec- 
tion, after remaining almost proportional to the loads, suddenly begins 
to increase rapidly. The extreme fiber stress at the thus established 
elastic limit is calculated the same as the ultimate extreme fiber stress, 
using the load on the beam at the elastic limit in place of the ultimate 
breaking load. 

The modulus of elasticity for rectangular sections is computed from 
the well-known formula, — 

WP 
-p__ 

4Dbh 3 
Where E=modilus of elasticity. 

D= deflection of beam in inches. 
W, 1, b and h same as atove. 

To find this modulus a tangent line is drawn to the strain diagram 
at its origin, and the co-ordinates of any point on this line used as the 
W and D from which to compute E. The modulus of elasticity is a true 
measure of the stiffness of the material, and is the most constant and 
reliable property of all kinds of engineering materials, and is a neces- 
sary means of computing all deflections or distortions under loads. 

Crushing or Compression Tests. — The endwise compression tests 
were made, as a rule, on sticks 4 in. square and 8 in. long, although 
some tests were made on sticks 4 in. square and 40 in. long. The ma- 
chine used was a Universal Testing machine. 

The crushing or compression tests across grain were made on sticks 
4 in. square and 6 in. long. The load is recorded when the limit of the 
distortion, i. e., indentation, is 15 per cent, of the height, i. e., thickness 
of timber compressed. 

The department has a machine for testing full-size columns with a 
capacity of 1,000,000 lbs., capable of crushing a timber column 12 to 14 
in. square, and up to a length of 36 ft. No tests had been made on this 
machine up to the spring 1893, the date of the last published results. 

Tensile Tests.— The tensile tests were made on a Universal Testing 
machine, the specimens being cut from the ends of previously broken 
beams, the section of specimens being 2%x% in. 



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676 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

Dr. Fernow summarizes the more important deductions, that can be 
made on the basis of the tests of Long-Leaf Pine, published up to 1893, 
as follows: 

"With the exception of tensile strength, a reduction of moisture Is 
accompanied by an increase in strength, stiffness, and toughness. 

"Variation in strength goes generally hand in hand with variation 
in specific gravity. 

"The strongest timber is found in a region lying between the pith 
and the sap, at about one-third of the radius from the pith in the butt 
log; in the top log the heart portion seems strongest. The difference in 
strength in the same log ranges, however, not over 12 per cent, of the 
average, except in crushing across the grain and shearing, where no re- 
lation according to radial situation is apparent. 

"Regarding the variation of strength with the height in the tree, it 
was found that for the first 20 to 30 feet the values remain constant, then 
occurs a more or less gradual decrease of strength, which finally, at the 
height of 70 feet, amounts to 20 to 40 per cent, of that of the butt log 
for the various exhibitions of strength. 

"In shearing and crushing across and parallel with the grain, prac- 
tically no difference was found. 

"Large beams appear 10 to 20 per cent, weaker than small pieces. 

"Compression tests seem to furnish the best average statement of 
value of wood, and if one test only can be made this is the safest. 

"The investigations into the effect of bleeding the trees for turpen- 
tine leave no doubt of the fact that bled timber is in no respect in- 
ferior to unbled timber." 

The following additional extracts from Dr. Fernow' s report, and the 
accompanying table herewith, copied from his report, will prove not 
only interesting and aid in defining the class of timber covered by these 
tests and called "Long-Leaf Pine," but will form a useful and valuable 
record, especially as the original publication (Bulletin No. 8) is out of 
print and difficult to obtain: 

"There are in the Southern Atlantic and Gulf States ten species of 
pine which are or can be cut into lumber. Two of these— the white 
pine (Pinus strobus L.) and the pitch-pine, also called yellow or black 
pine (Pinus rigida Mill.) — occur only in small bodies on the Allegheny 
mountains, from Virginia down to Northern Georgia, being rather North- 
ern pines. Three — the Jersey or scrub-pine, occasionally also called 
short-leaf or spruce-pine (Pinus virginiana Mill.) along the coast to 
South Carolina; the sand, scrub, or spruce-pine (Pinus clausa (Engelm.) 
Sarg.), found in a few localities in Florida; and the pond, also called 
loblolly or Savannah pine (Pinus serotina Mx.) along the coast from 
North Carolina down to Florida— occur either so sparingly that they do 
not cut any figure on the lumber market, or do not often produce siza- 
ble trees for saw-logs. 

"There remain, then, five distinctly Southern species which are ac- 
tually cut for lumber; one of these, the spruce-pine, also called cedar 
pine or white pine (Pinus glabra Walt.) probably does not reach the 
market except by accident. But the other four may be found now in 
all the leading markets of the East. 

"There exists considerable confusion among architects, builders, 
engineers, as well as dealers in lumber and lumbermen themselves, as 
to the identity of these species and their lumber. The confusion arises 
mainly from an indiscriminate use of local names, and from ignorance 
as to the differences in characteristics of their lumber as well as the 
difficulty in describing these. 

"The table herewith, showing the names, which have been found 
applied to the four species furnishing Southern pine lumber, will most 



TIMBER TESTS. 677 

readily exhibit the difficulty arising from misapprehension of names. 
These names are used in the various markets and in various localities 
in the home of the trees. Where possible the locality in which the name 
is used has been placed in brackets by the side of the name." 

Prof. J. B. Johnson makes the following statements regarding the 
extensive tests made under his charge as reported above: 

"The long-leaf pine timber is specially fitted to be used as beams, 
joists, posts, stringers in wooden bridges, and as flooring when quar- 
ter-sawed. It is probably the strongest timber in large sizes to be had 
in the United States. In small selected specimens, other species, as oak 
and hickory, may exceed it in strength and toughness. Oak timber, 
when used in large sizes, is apt to be more or less cross-grained, knotty, 
and season-checked, so that large oak beams and posts will average 
much lower in strength than the long-leaf pine, which is usually free 
from these defects. The butt cuts are apt to be windshaken, however, 
which may weaken any large beams coming from the lower part of the 
tree. In this case the beam would fail by shearing or splitting along this 
fault with a much smaller load than it would carry without such de- 
fect. These wind shakes are readily seen by the inspector, and sticks 
containing them are easily excluded, if it is thought worth while to do 
so. For highway and railway wooden bridges and trestles, for the en- 
tire floor system of what is now termed 'mill' or 'slow-burning' construc- 
tion, for masts of vessels, for ordinary floors, joists, rafters, roof -trusses, 
mill-frames, derricks, and bearing piles; also for agricultural machin- 
ery, wagons, carriages, and especially for passenger and freight cars, 
in all their parts requiring strength and toughness, the long-leaf pine is 
peculiarly fitted. Its strength, as compared to that of short-leaf yellow 
pine and white pine, is probably very nearly in direct proportion to 
their relative weight, so that pound for pound all the pines are probably 
of about equal strength. The long-leaf pine is, however, so much heavier 
than these other varieties that its strength for given sizes is much 
greater. 

"A great many tests have now been made on short-leaf and on lob- 
lolly pine, both of which may be classed with long-leaf as 'Southern 
yellow pine,' and from these tests it appears that both these species are 
inferior to the long-leaf in strength in about the ratio of their specific 
gravities. In other words, long-leaf pine (Pinus palustris) is about one- 
third stronger and heavier than any other varieties of Southern yellow 
pine lumber found in the markets. It is altogether likely that a consid- 
erable proportion of the tests heretofore made on 'Southern yellow 
pine' have been made on one or both of these weaker varieties." 

APPENDIX D. 

PROFESSOR LANZA'S FULL-SIZE TRANSVERSE TESTS. 

Professor Gaetano Lanza, of the Massachusetts Institute of Tech- 
nology, author of "Applied Mechanics," and one of the best known 
writers and experimenters on the strength of timber in this country, 
obtained the following results from full-size transverse tests made in 
his Boston laboratory. 

a. Transverse strength of spruce. 

From sixty-eight full-size tests of spruce beams:— 

Ultimate breaking extreme fibre stress in pounds per square inch, 

2,b28 to 8,748; average, 5,046. 

Modulus of elasticity in pounds per square inch, 897,961 to 1,588,548; 

average, 1,332,500. 



678 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

For the calculation of deflection of a spruce beam under a given 
load to be applied for a long time, the modulus of elasticity should be 
assumed as 666,300. 

Professor Lanza states that, judging from results of spruce obtained 
from Boston, Mass., lumber yards, the ordinary run of spruce would 
not allow a higher ultimate breaking extreme fibre stress than 3,000 
pounds, and even that might in some cases be too high; that the very 
best selected stock at any one lumber yard would not allow over 4,000. 
pounds to be used; and to allow 5,000 pounds per square inch to be used 
special sticks from different dealers would have to be collected, if a con- 
siderable amount of such lumber were desired. 

b. Transverse strength of yellow pine. 

From fifty-one full-size tests of yellow pine beams:— 

Ultimate breaking extreme fibre stress in pounds per square inch, 
3,963 to 11,360; average, 7,486. 

Modulus of elasticity in pounds per square inch, 1,162,467 to 2,380,- 
096; average, 1,757,900. 

For the calculation of deflection of a yellow pine beam under a given 
load to be applied for a long time, the modulus of elasticity should be 
assumed as 878,950. 

Professor Lanza states that for yellow pine of fair quality it would 
not be correct to use for the ultimate breaking extreme fibre stress a 
number greater than 5,000 pounds per square inch, especially for large 
sizes, such as 9x14 inches, 12x16 inches, etc. Although the average re- 
sult from the tests showed 7,486 pounds, nevertheless in the case of one 
particular beam it was 5,300, notwithstanding the fact that this beam 
was quite free from knots, cracks, crooked grain, and other defects, and 
had been selected as one of exceptionally good quality. 

c. Transverse strength of white oak. 

From thirty-six full-size tests of white oak cut in Pennsylvania and 
Ohio:— 

Ultimate breaking extreme fibre stress in pounds per square inch, 
3,535 to 7,834; average, 5,803. 

Modulus of elasticity in pounds per square inch, 744,774 to 1,777,500; 
average, 1,131,100. 

d. Transverse strength of white pine. 

From thirty-seven full-size tests of white pine:— 

Ultimate breaking extreme fibre stress in pounds per square inch, 
2,156 to 7,251; average, 4,451. 

Modulus of elasticity in pounds per square inch, 727,200 to 1,565,000; 
average, 1,122,000. 

Eight full-size tests of kiln-dried western white pine showed an av- 
erage ultimate breaking extreme fibre stress of 5,482, and an average 
modulus of elasticity of 1,183,037. 

e. Transverse strength of hemlock. 

From seventeen full-size tests of eastern and Vermont hemlock:— 
Ultimate breaking extreme fibre stress in pounds per square inch, 

2,059 to 6,535; average, 3,825. 

Modulus of elasticity in pounds per square inch, 4 "2,670 to 1,327,200; 

average, 922,250. 






TIMBER TESTS. 679 

f. Time tests for deflection of timber beams under transverse strain. 

From a large number of full-size time tests on spruce and yellow 
pine beams centrally loaded for different periods, some over half a year, 
Professor Lanza concludes that the deflection of a timber beam under 
a long-continued application of the load, may be two or more times that 
assumed when the load was first applied; and that, in order to com- 
pute it by means of the ordinary deflection formulae, the modulus of 
elasticity should be assumed at not more than one-half the value ob- 
tained from quick tests. 

APPENDIX E. 
MISCELLANEOUS FULL-SIZE TESTS. 

a. Some English full-size transverse tests of timber beams, made by 
Messrs. Edwin Clark, and C. Graham Smith, show the following average 
values for the ultimate breaking extreme fibre stress, and for the modu- 
lus of elasticity, both in pounds, per square inch:— 

American red pine.... 3 tests; fibre stress, 4,842; mod. elast. 1,204,943 

Memel fir 2 tests; fibre stress, 5,274; mod, elast. 1,855,900 

European pitch pine.. .4 tests; fibre stress, 6,984; mod elast. 2,046,275 
European red pine.... 2 tests; fibre stress, 4,572; mod. elast. 1,247,000 
Quebec yellow pine... 4 tests; fibre stress, 4,491; mod. elast. 1,309,833 
Baltic fir 2 tests; fibre stress, 5,454; mod. elast. 1,507,850 

b. Messrs. David Kirkaldy & Son, London, England, made a series 
of full-size tests of American white oak in 1884, for the International 
Forestry Exhibition, Edinburg, 1884, with following results: — 

All sticks, scant four and one-half inches by scant twelve inches; 
five tests for each average result. 

Transverse tests, ultimate breaking extreme fibre stress in pounds 
per square inch: — five feet span, 6,890 pounds; eleven feet span, 8,550 
pounds. 

Compression tests, ultimate breaking stress in pounds per square 
inch:— twenty-five inches long, or about six diameters, 3,285 pounds; 
fifty inches long, or about eleven diameters, 3,418 pounds; 100 inches 
long, or about twenty-three diameters, 2,891 pounds. 

APPENDIX F. 

LONGITUDINAL SHEARING UNDER TRANSVERSE STRAIN. 

Beams loaded transversely sometimes fail by shearing longitudinally 
along the neutral axis. The intensity i, of the longitudinal shearing 
stress in pounds per square inch in a rectangular beam, is expressed by 
the formula: — 

3F 

~2bh 

where F equals total vertical shear in pounds at the point of beam 
selected; and b and h respectively the breadth and height of beam in 
inches. For a center load, W, this formula becomes:— 

3W 

~4bh 

a. Professor Lanza found the following average calculated values 
for the ultimate breaking longitudinal shearing stress in pounds per 
square inch for the different full-size beam tests conducted in his labora- 
tory:— 



68o AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

For beams that failed by longitudinal shearing— 

9 spruce beams, average T 198 pounds 

5 yellow pine beams, average 222 pounds 

2 white oak beams, average 266 pounds 

3 white pine beams, average 151 pounds 

For beams that failed by flexure, and not by longitudinal shearing— 

58 spruce beams, average 182 pounds 

45 yellow pine beams, average 231 pounds 

31 white oak beams, average 176 pounds 

33 white pine beams, average 134 pounds 

17 hemlock beams, average 123 pounds 

b. Professor Charles B. Wing, Leland Stanford University, Califor- 
nia, published in Engineering News, March 14, 1895, an account of cer- 
tain full-size tests of Douglas fir beams, two of which failed by longitu- 
dinal shearing under transverse loading, the value of the longitudinal 
shearing stress, calculated by the formula, having been respectively 185 
and 143 pounds per square inch. The average calculated longitudinal 
shearing stress for nine of the full-size beams, that failed by flexure, 
was at the time of breaking 160 pounds per square inch, or probably 
very near the ultimate limit. Professor Wing concludes, from these re- 
sults, that the danger of failure by longitudinal shearing should not be 
lost sight of in using large timber beams in flexure. 

APPENDIX G. 

PROFESSOR LANZA'S FULL-SIZE TESTS OF TIMBER COLUMNS. 

a. An extensive series of full-size tests of wooden mill-columns 
were made in 1882 at the United States arsenal, Watertown, Mass., by 
Professor Lanza, for the Boston Manufacturers' Mutual Fire Insurance 
Company, the results having been published in a special pamphlet. The 
columns were generally round, and the ends as a rule flat. The least 
diameters varied from about 6 to 11 inches, the lengths from about 11 to 
14 feet. A series of tests on blocks, 2 feet long, the same size as the col- 
umns, were also made, with the result that the ultimate crushing 
strength of the short blocks was very nearly practically the same as for 
the columns tested, for which the quotient of length divided by the least 
diameter varied from about 15 to about 25. In other words, colloquially 
speaking, the tests covered columns of about 15 to 25 diams. 

The results show as follows: 

Yellow pine posts and blocks, 18 tests: Ultimate breaking crushing 
strength in pounds per square inch, 3,604 to 5,452; average, 4,544; modu- 
lus of elasticity for crushing in pounds per square inch, 1,631,035 to 
2,443,411; average, 1,996,351. 

White oak posts and blocks, 10 tests: Ultimate breaking crushing 
strength in pounds per square inch, 3,132 to 4,450; average, 3,470; mod- 
ulus of elasticity for crushing in pounds per square inch, l,104,93o to 
1,748,817. 

Old and seasoned white oak posts (ten of which had been in use 
about 25 years), partly with uneven end bearings so as to represent ac- 
tual conditions existing frequently in old structures, 18 tests: Ultimate 
breaking crushing strength in pounds per square inch, 2,943 to 6,147; av- 
erage, 3,957 pounds; modulus of elasticity for crushing in pounds per 
square inch, 1,448,964 to 2,138,804. 

Professor Lanza states, that in all these tests the columns gave way 
by direct crushing, and hence that the strength of columns of these ra- 
tios of length to diameter can properly be found by multiplying the 



TIMBER TESTS. 68 1 

crushing strength per square inch of the wood by the area of the section 
In square inches. 

A set of tests was made of columns with eccentric loading, showing 
a great falling off of strength, due to the eccentricity of the load. 

Professor Lanza offers among others the following conclusions, 
which are of interest for railroad work: 

"The strength of a column of hard pine or oak, with flat ends, the 
load being uniformly distributed over the ends, and of the diameters 
tested, is practically independent of the length, for the ratios of length 
to diameter used in the tests, such columns giving way practically by di- 
rect crushing; the deflection, if any, being as a rule very small, and ex- 
erting no appreciable influence on the breaking strength. 

"The crushing strength per square inch varies considerably in speci- 
mens of different degrees of seasoning, also in large and small speci- 
mens. The average crushing strength of such yellow pine posts as were 
tested, not thoroughly seasoned, and not very green, is about 4,400. 
pounds; whereas for such oak as was furnished me, which was green 
and knotty, but no more so than is usual for use in building, the average 
Is about 3,200 pounds. 

"I would recommend the use of iron caps and pintles, instead of 
wooden bolsters, as wood is very weak to resist crushing across the 
grain, and the wooden bolster will fail at a pressure far below that 
which the column is capable of resisting, and the unevenness of the 
pressure brought about by the bolster is so great as to sometimes crack 
the column at a pressure far below what it would otherwise sustain. 

"Any cause which operates to distribute the pressure on the ends 
unevenly, or to force its' resultant out of center, is a source of weak- 
ness, and brings about a very considerable deflection, which exerts an 
important influence in reducing the breaking strength." 

b. Several tests of some well-seasoned old spruce round struts, of 
excellent quality, with even flat end bearings, made at the TVatertown 
arsenal for the Jackson Company, showed an average ultimate break- 
ing crushing strength of 5,071 pounds per square inch, the diameter be- 
ing slack 6 inches and the length full 10 feet, or, in other words, length 
of strut about 21 diams. 

c. Professor Lanza presented at the December, 1894, meeting of the 
American Society of Mechanical Engineers the results of his latest tests 
of thirteen full-size fairly well-seasoned spruce columns of fair average 
quality obtained from Boston lumber yards. Rectangular specimens, 
about 8 to 10 inches wide, 8 to 12 inches high, and 6 to 18 feet spans. 
The ratios of length to least side varied from about 9 to 27. The speci- 
mens with the higher ratios broke by deflection, those with the lower 
ratios by crushing. 

The results were as follows: 

Ultimate breaking crushing stress in pounds per square inch, 1,969 
for 15 diams. to 3,195 for 9 diams.; average 20 to 27 diams., 2,424; aver- 
age 15 to 20 diams., 2,670; average 10 to 15 diams., 2,442; average 9 
diams., 2,875; grand average, 2,540. Modulus of elasticity in pounds 
per square inch, 834,270 to 1,656,300; average, 1,280,260. 

APPENDIX H. 

U. S. GOVERNMENT FULL-SIZE TESTS OF TIMBER COLUMNS. 

a. The most extensive and reliable set of tests of timber struts ever 
undertaken in this country were made by the United States govern- 
ment in 1880 to 1883, under the direction of Col. T. T. S. Laidley, U..S. 
A., at the United States arsenal, Watertown, Mass., recorded in Exec. 



682 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

Doc. No. 12, 47th Congress, 1st session, and Exec. Doc. No. 1, 47th Con- 
gress, 2d session. The tests covered full-size white pane and yellow 
pine rectangular struts with flat end bearings. The areas of the sticks 
varied from 27 to 235 square inches, and the lengths from 4 to 28 feet. 
There were several hundred full-size sticks broken. 

b. Prof. William H. Burr, of Columbia College, New York City, ana- 
lyzes these government tests of columns as follows: 

Flat end yellow pine columns were observed to begin to fail with 
deflection at a length of about 22 diameters. The short yellow pine col- 
umns, of a less length than 22 diameters, gave an ultimate breaking 
compression stress in pounds per square inch of 3,430 to 5,677, averag- 
ing 4,442. The long yellow pine columns of a length from 22 to 62 diame- 
ters gave values respectively from about 3,500 pounds to 1,700 pounds. 

Plat end white pine columns began to fail with deflection at a length 
of 32 diameters. Thirty short white pine columns of- a less length than 
32 diameters failed generally at knots by direct compression, and gave 
an ultimate breaking compression stress in pounds per square inch of 
1,687 to 3,700, averaging 2,414. The long white pine columns of a length 
from 32 to 62 diameters gave values respectively from about 2,000 
pounds to 1,000 pounds. 

A large number of tests were made on compound columns formed of 
two or three sticks, separated by packing blocks and bolted together at 
the ends and at the center. The tests showed that the compound col- 
umns possessed essentially the same ultimate resistance per square inch 
as each component stick considered as a column by itself. 

c. Some additional full-size tests, made in 1881 for the United States 
government by Colonel Laidley at Watertown arsenal, on timber struts, 
showed as follows: 

Very straight grained yellow pine, 20 years seasoning, 12 tests, ulti- 
mate breaking compressive stress in pounds per square inch, 5,593 to 
8,644; average, 7,386. 

Very slow growth yellow pine, 3 tests, ultimate breaking compres- 
sive stress in pouDds per square inch, 7,820 to 10,250; average, 9,339. 

Very green and wet yellow pine, 3 tests, ultimate breaking compres- 
sive stress in pounds per square inch, 2,795 to 3,180; average, 3,015! 

Spruce, thoroughly seasoned, full-size struts, 12 tests, ultimate 
breaking compressive stress in pounds per square inch, 3,967 to 5,754; 
average, 4,873. 

APPENDIX I. 

PROFESSOR BURR'S FORMULAE FOR TIMBER COLUMNS. 

Professor William H. Burr, of Columbia College, New York, author 
of "Elasticity and Resistance of the Materials of Engineering," offers 
the following formulae for timber struts based upon the above govern- 
ment tests, in which formulae 

p = ultimate breaking compression str3s? in pounds per square 

inch; 
1 = length of strut in inches; 
d = least side or diameter of strut in inches; 
s = safe working compression stress in pounds per square inch. 

1 
For yellow pine p = 5,800—70— 

d 

1 
For white pine p = 3,800—47— 

d 



TIMBER TESTS. 



683 



For wooden railway structures, with a factor of safety of about 8, 
these formulae will read for the safe working stress: 

1 



For yellow pine 


s = 750—9— 




d 
1 


For white pine 


s = 500—6- 




d 



For temporary structures, such as bridge falseworks carrying no 
traffic, with a factor of safety of about 4, these formulae will read for 
the safe working stress: 



For yellow pine 
For white pine 



s = 1,500—18— 

d 

1 

s = 1,000—12— 

d 

The preceding formulas are to be used only between the limits of 
11 11 

20 — and 60— for yellow pine, and between 30 — and 60 — for white 

d d d d 

pine. 

1 1 

For short columns below 20 — and 30 — , respectively for yellow and 

d d 

white pine, use the following unit stresses in pounds per square inch. 





Ultimate. 


Safe for railway 
bridges. 


Safe for temporary 
structures. 


Yellow pine — 
White pine .... 


p = 4400 
p = 2400 


s = 550 
s = 300 


. s = 1100 
s = 600 



All these values are applicable to good average lumber for the prac- 
tical purposes indicated. 

APPENDIX J. 

PROFESSOR ELY'S FORMULAE FOR TIMBER COLUMNS. 

Mr. Edward F. Ely, instructor Massachusetts Institute of Technol- 
ogy, Boston, gives the following rule and unit co-efficients for timber 
columns based upon the above mentioned government tests. The aver- 
age and the lowest results of these tests were plotted and the following 
rule established from the diagrams: 

Total breaking strength of column in pounds equals area of section 
in square inches multiplied by the ultimate breaking crushing strength 
in pounds per square inch. 

The ultimate breaking crushing strength in pounds per square inch 
for each particular case is obtained from the following table, it being 
dependent on the ratio of the length to the least side of the rectangular 
strut. 



684 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 



Kind of Timber, 


Length in inches divid- 
ed by least side cf 
strut in inches. 


Ultimate crushing 
strength in lbs. per 
square inch. 




Oto 10 
10 to 35 
35 to 45 
45 to 60 


2,500 




3,000 
1,500 
1,000 


Yellow Pine 


to 15 
15 to 30 
30 to 40 
40 to 45 
45 to 50 
50 to 60 


4,000 




3,500 
3,000 
2,500 
2,000 
1,500 



APPENDIX K. 
PROFESSOR STANWOOD'S FORMULAE FOR TIMBER COLUMNS. 



Mr. James H. Stanwood, instructor Massachusetts Institute of Tech- 
nology, published in The American Architect and Building News of 
April 9, 1892, and of March 10, 1894, the following formulae for timber 
struts based upon the full-size U. S. government tests made at the 
Watertown Arsenal, and also on full-size tests of Professor Lanza. The 
experimental data for full-size white and yellow pine struts, on which 
the formulae are based, are quite extensive and reliable, while there is 
not so much information at hand covering full-size tests of oak and of 
spruce columns. 

The formulae for the ultimate breaking crushing strength per square 
Inch of columns with square ends are as follows: 



For yellow pine 



For white pine 



s = 4,250 — 43^- 



s = 3,150 — 40- 



Where s == ultimate breaking crushing stress in pounds per square 
inch; 
1 = length of col lmn in inches; 
d — least diameter in inches. 
The following safe working formulae are recommended: 
For yellow pine or white oak (using a factor-of-safety of about 4*4) 

1 
s = 1,000 — 10— 
d 

For white pine or spruce (using a factor-of-safety of 4) 

1 
s = 800 — 10— 
d 
Where s = allowable safe working crushing stress in pounds per 
square inch, and 1 and d, same as above. 

APPENDIX L. 

C. SHALER SMITH'S FORMULAE FOR TIMBER COLUMNS. 

Professor Burr, in his book "Elasticity and Resistance of the Mate- 
rials of Engineering," gives certain data relative to C. Shaler Smith's 



TIMBER TESTS. 685 

formula for timber columns that will prove very interesting owing to the 
extensive use that has been made of this formula. 

Mr. C. Shaler Smith conducted, during the winter of 1861-'62, a series 
of over 1,200 tests of full-size yellow pine square and rectangular col- 
umns for the ordnance department of the Confederate government, 
from which his well-known formula for timber struts was developed. 

The tests were grouped as follows: 

1. Green, half-seasoned sticks answering to the specification "good 
merchantable lumber." 

2. Selected sticks reasonably straight, and air-seasoned under cover 
for two years and over. 

3. Average sticks cut from lumber which had been in open air ser- 
vice for four years and over. 

The formulae for these three groups were,— 



For No. 1: 



5,400 



1 + 



1 1» 



250 d a 

8,200 



For No. 2: 
Fof No. &j 


p = 

1 1* 

1 + 

300 d a 

5,000 

n — 


V — 

1 1» 

250 d* 



Where 1 = length of column in inches; 

d = least side or diameter of column in inches; 
p = ultimate breaking compressive stress in pounds per 
square inch. 

In order to provide against ordinary deterioration, and also reckless 
building, bad workmanship, etc., Mr. Smith recommended the formula 
for group No. 3 as the best for general application. 

He also recommended that the factor-of-safety shall be the square 
root of the quotient of the length divided by the least diameter until 
twenty-five diameters are reached, and five thence forward to sixty di- 
amters, which last limit is the extreme for good practice. 

Mr. Smith's formula formed the basis of the principal timber column 
tables in "Trautwine's Pocket Book," but comparison with more recent 
results of full-size tests will show that it is very safe, unless very bad 
workmanship or an unusual set of conditions prevail. 

Mr. Smith recommended for white pine columns the use of formula 
No. 3 with 3,000 substituted for the constant 5,000. 

APPENDIX M. 

PROFESSOR BOVEY'S FULL-SIZE TESTS OF CANADIAN DOUG- 
LAS FIR, RED PINE, WHITE PINE, AND SPRUCE. 

Professor Henry T. Bovey, of McGill University, Montreal, Can . 
presented a most valuable and voluminous paper on "The Strength of 
Canadian Douglas Fir, Red Pine, White Pine, and Spruce," to the Cana- 
dian Society of Civil Engineers, Transactions, Vol. IX., January 25, 



686 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

1895 based upon the experiments conducted for a period of more than 
two 'years in the testing laboratories of McGdll University. The paper 
covers 110 pages of the printed transactions and gives minute informa- 
tion as to the manner of conducting the tests, the origin, quality, and 
condition of the timber tested, as also full and detail results of the tests. 
A synopsis of this valuable paper is all that can be attempted here. Par- 
ties directly interested should obtain the full report by addressing Pro- 
fessor Bovey or the Canadian Society of Civil Engineers at Montreal. 

Professor Bovey makes the following general remark:— "The tables 
showing the deflections of beams under transverse loading, and also the 
tables showing the extension of specimens under direct tension, tend to 
prove conclusively the .statement made by the author many years ago, 
i e., that timber, unlike iron and steel, may be strained to a point near 
the breaking point without being seriously injured. It will be observed 
that in almost all cases the increments of deflection and extension, al- 
most up to the point of fracture, are very nearly proportional to the in- 
crements of load, and it seems impossible to define a limit of elasticity 
for timber. This probably accounts for the continued existence of many 
timber structures in which the timbers have been and are still contin- 
ually subjected to excessive stresses, the factor of safety being oftui 
less than 1V>. Whether it is advisable so to strain timber is another 
question, and experiments are still required to show how timber is af- 
fected by frequently repeated strains." 

The Douglas fir used in these tests came from British Columbia. 
The red pine was cut in 1893 in the neighborhood of the Bonnechere 
River, Nipissing District, County Renfrew, Ontario (west of the city of 
Ottawa). The white pine came from the valleys of tributaries of the 
Ottawa River, northerly and westerly from the city of Ottawa. The 
new spruce was cut near the Skeena River, British Columbia, on the 
Pacific coast, about 600 miles north of Victoria. The old spruce was 
from the Province of Quebec, west of Maine. 

I. TRANSVERSE STRENGTH. 

In the transverse tests the results given are the calculated "Maxi- 
mum Skin Stress" (ultimate breaking extreme fibre stress) in pounds 
per square inch, and the "Co-efficient of Elasticity" (modulus of elas- 
ticity) in pounds, corresponding to the actual breaking load applied at 
the center of the span. 

All the tests were made on large size sticks with spans varying from 
5y 2 feet to 24 feet. 

The weight of timber is given in pounds per cubic foot at date of 
♦ test. 

a. Transverse strength of Canadian Douglas fir. 

Large size sticks, spans 5% to 17 feet, breaking load applied cen- 
trally. 



TIMBER TESTS. 



687 



Maximum skin 
stress lbs. per 
square inch. 



New timber, ( minimum. . 
Specially -j maximum. . 
Selected, ( average 
Four tests, 

New timber, ( minimum. 
First quality, j maximum 
Fifteen tests. ( average. . . 

Old trestle timber: 
6% years in use 

8 years in use 

9 years in use 

11 years in use 



8,020 

10,441 

9,054 



4,027 

8,382 
6,081 



8,135 
7,339 

7,086 
4,613 



Co efficient 

elasticity. 

Pounds. 



of Weight 
in lbs. 
per cu. 
foot. 



1.93^,500 
2,178,100 
2,036,529 

926,500 
1,770,563 
1,431,209 



1,201,620 

1,878.950 

1,665,560 

949,270 



38.92 
41.22 
40.02 



28.27 
37.80 
33.80 



32.80 
38.59 
33.75 
33.11 



Professor Bovey recommends the following data for adoption in 
practice: 

"In the case of specially selected timber, free from itnots, with 
sound, clear, and straight grain, and cut out of the log at a distance 
from the heart,— 

Average weight in lbs: per cubic foot = 40. 

Average coefficient of elasticity in lbs. per square inch == 2,000,000. 
Average maximum skin stress in lbs. per square inch = 9,000. 
Safe working skin stress in lbs. per square inch = 3,000. 

"In the case of first quality timber, such as is ordinarily found in 
the market.- 
Average weight in lbs. per cubic foot = 34. 

Average coefficient of elasticity in lbs. per square inch = 1.430,000. 
Average maximum skin stress in lbs. per square inch = 6,000. 
Safe working skin stress in lbs. per square inch = 2,000. 



"In specifying these data it will be observed that 3 is adopted as 
the factor of safety. Upon this hypothesis the factor of safety for the 
stick giving the minimum skin stress is more than 2, and this, in the 
opinion of the author, is an ample factor for a material which experience 
and all experiments show, may be strained without danger very nearly 
up to the point of fracture. 

"Further, the results obtained in the experiments with the old string- 
ers show that the strength of the timber had been retained to a very 
large extent, and that the rotting had not extended to such a depth be- 
low the skin as to sensibly affect the efficiency of the sticks, which still 
possessed ample strength for the work which they were designed to do. 

"If 2 is adopted as the factor of safety, and, in the opinion of the 
author, 2 is an ample factor for the great majority of cases, the rotting 
(in these old stringers) might extend without danger to a depth of 3.4 
inches. 

"Again, it will be observed that the skin stress and the elasticity are 
subject to a wide variation. This variation is due to many causes, of 
which the most important are the presence of knots, obliquity of grain, 
and, more than all, the locality in which the timber was grown, the 
original position of the stick in the log from which it was cut, and the 
proportion of hard to soft fibre, or of the summer to the spring growth. 
The tensile, shearing, and compressive experiments upon specimens cut 



688 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

out of different parts of the same log all show that the timber near the 
heart possesses much less strength and stiffness than the timber at a 
distance from the heart. 

"A careful study of the results obtained up to date would seem to 
indicate that the best classification defining the strength of the timber 
would be found by dividing the section of a log into three parts by 
means of two circles, with the heart as the center, and by designating 
the central portion as third quality, the portion between the two circles 
as second quality, and the outermost portion as first quality." 

A most interesting paper on the structural characteristics of Doug- 
las fir from a botanical standpoint was read by Professor Penhallow, 
F. R. S. C, at the meeting of the Royal Society of Canada, in Ottawa, 
in 1894, in connection with a paper read by Professor Bovey on the 
strength of the timber (Transactions Royal Society of Canada, Section 
III., 1894, Papers Nos. 11. and III.). 

b. Transverse strength of Canadian red pine. 

Large size sticks; spans, 13 to 17% feet; breaking load applied cen- 
trally. 





Maximum skin 
stress lbs. per 
square inch. 


Co-efficient of 
elasticity. 
Pounds. 


Weight 
in lbs. 
per cu. 
foot. 


New timber, 
6x7 in to 
6x13 in., 


< maximum 

( average 


3,937 
6,752 
5,137 

4,339 
6,928 
5,725 


1,198,550 
1,802,633 
1,434,747 

1,575,200 
1,784,800 
1,648,519 


30.96 
37.55 
34.78 


6 tests. 

New timber, 
3x8 in. to 
3x11 in., 
4 tests. 


( minimum 

< maximum 

( average 


31.56 
37.69 
34.43 



Professor Bovey recommends the following data for adoption in 
practice: 

Average weight in lbs. per cubic foot = 34.6. 
Average coefficient of elasticity in lbs. per square inch = 1,430,000. 
Average maximum skin stress in lbs, per square inch = 5,100. 
Average safe working skin stress in lbs. per square inch (3 being 
the factor of safety) = 1,700. 

"In the accounts of the several beams it will be observed that the 
failures are almost invariably due to the crippling of the material on the 
side in compression, indicating that the tensile strength of the timber 
exceeds its compressive strength, and this was subsequently verified by 
the direct tension and compression experiments." 

e. Transverse strength of Canadian white pine. 



Sizes 9 in. x 15 in. and 9 in. x 18 in.; spans, 8y 2 to 24 feet; breaking 
load applied centrally. 



TIMBER TESTS. 



689 



New Timber, ( Minimum 

15 tests. ■< Maximum 

( Average. . 

Old Stringers, ( Minimum 
in use 8 years, < Maximum 
3 tests. " ( Average. . 



Maximum skin J Co-efficient of 
stress lbs. per Elasticity, 
square inch. Pounds. 



2,500 
4,936 
3,388 

2,495 

3,589 
3,099 



433,250 

1,184,240 

754,265 

650,930 
982,480 
854,333 



Weight 
in lbs. 
per cu. 
foot. 



33.64 
41.49 

37.88 

26.08 
28.30 
27.54 



Professor Bovey recommends the following data for adoption in 
practice: 

Average weight in lbs. per cubic foot = 37.8. 
Average co-efficient of elasticity in lbs. per square inch = 754,000. 
Average maximum skin stress in lbs. per square inch = 3,300. 
Average safe working skin stress in lbs. per square inch (3 being 
the factor of safety) == 1,100. 

"Further experiments will probably show that these data require 
some modification. The actual skin stress and coefficients of elasticity 
are certainly greater than those given above." 

d. Transverse strength of Canadian spruce. 



trally 



Large size sticks; spans 10 to 24 feet; breaking load applied 

1-w 



cen- 



New Timber, j Minimum . 
3 tests, all -j Maximum, 

from same log. ( Average. . 



Old Bridge and f Minimum 
Culvert Stringers, I ™ U m 

5tests yearS,nUSe 'l Average -- 



Maximum skin 1 Co-efficient of 



stress lbs. psr 
square inch. 



4,614 
5,908 
5,120 

2 934 
5,709 
3,875 



Elasticity. 
Pounds. 



Weight 
in lbs. 
per cu. 
foot. 



1,011,460 
1,528,499 
1,203,633 

905,601 
1,352,250 
1,189,800 



26.61 
26.61 
26.61 

26.47 
33.09 
29.15 



II.— COMPRESSIVE STRENGTH. 



The tests for compressive strength were made on sticks with from 
5 to 40 square inches of cross-section, and in lengths from a few inches 
up to GV 2 feet. The result given in each case is the ultimate breaking 
load in pounds per square inch of cross-section of stick. 

The experiments were made chiefly with columns cut out of the 
sticks already tested transversely. These columns were carefully ex- 
amined to see that the previous test of stick had caused no injury. 

Professor Bovey states that the following inferences from the com- 
pressive tests may be drawn: 

"The compressive strength of Douglas fir and of other soft timbers 
is much less near the heart than at a distance from the heart. The 



6qo AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

compressive strength of the timber increases with the density of the 
annular rings. 

"When knots are present in a timber column, the column will al- 
most invariably fail at a knot, or in consequence of the proximity of a 
knot. 

"Any imperfection, as, for example, a small hole made by an ordi- 
nary cant hook, tends to introduce incipient bending or crippling. 

"When the failures of average specimens commence by an initial 
bending, the compressive strengths of columns of about 10 to 25 diam- 
eters in length agree very well with the results obtained by Gordon's 
formula, the coefficients of direct compressive strength per square inch 
being 6,000 pounds for Douglas fir, and 5,000 pounds for white pine. 

"Gordon's formula, however, is not at all applicable in the case of 
specially good or bad specimens. It is often found that a very clear, 
sound specimen, of even more than 20 diameters in length, will show no 
signs of bending, but will suddenly fail by crippling under a load as 
great as that sufficient to crush a shorter specimen. 

"The greatest care should be observed in avoiding obliqueness of 
grain in columns, as the effective bearing area, and therefore also the 
strength, are considerably diminished. 

"If the end bearings are not perfectly flat and parallel, the columns 
will in all probability fail by benddng concave to the longest side. 

"The average strength per square inch, independent of the ratio of 
length to diameter, is, — 

New Douglas fir 5,974 lbs., average of 122 tests 

Old Douglas fir 6,205 lbs., average of 54 tests 

New red pine 4,067 lbs., average of 35 tests 

New white pine 3,843 lbs., average of 68 tests 

Old white pine 2.772 lbs., average of 56 tests 

New spruce (British Columbia) 3,617 lbs., average of 69 tests 

Old spruce 5,136 lbs., average of 20 tests 

"It should be pointed out that none of the old Douglas fir columns 
exceeded 4.4 diameters in length, while the great majority of the new 
Douglas fir columns were from 4 to 25 diameters in length. This ex- 
plains the reason of the greater average compressive strength of the old 
Douglas fir. A similar remark applies to the new and old spruce." 

III.— TENSILE STRENGTH. 

The tests for tensile strength were made on uninjured pieces of the 
beams previously broken by transverse strain. The specimens were 
less than one square inch in cross-section. Particular attention was 
paid to the effect of repeated loadings, also to a, comparison of strengcn 
and stiffness in different portions of the same log. The recorded results 
are too voluminous to be given here in detail. 

Professor Bovey states that the results of the tensile tests will 
show :— 

"That the increments of extension, up to the point of fracture, are 
almost directly proportional to the increments of load. 

"That the presence of knots is most detrimental both to the strength 
and to the stiffness, inasmuch as they practically diminish the effective 
sectional area, and also produce a curvature in the grain. 

"That wood near the heart possesses much less strength, and much 
less stiffness than that more distant from the heart. 

"^hat the strength and stiffness are also dependent upon the propor- 
tion of summer to spring growth. 

"That irregularities of readings, both with the extensometer and. 



TIMBER TESTS. 691 

with the rule, are chiefly due to the presence of a knot, or to curly or 
oblique grain caused, by a knot." 

a. Tensile strength of Canadian Douglas fir. 

Owing to the small size of the specimens, the variations in the qual- 
ity of the material, especially the presence of a knot or curly or oblique 
grain, cause a most marked difference in the recorded tensile breaking 
weight in pounds per square inch of cross-section. 

The results of seventy-one tests of new Douglas fir vary from 2,485 
to 18.S56 pounds; averaging 11,612 pounds. 

If the thirteen results less than 8,000 pounds be excluded, as being 
clearly caused by imperfections in the material, the average of the re- 
maining fifty-eight tests will be 12,955. 

To show that the recorded maximum of 18.856 pounds is not a phe- 
nomenon or an error, it would be well to mention that there are fifteen 
results from 15,000 to 18.856 pounds; namely, nine above 15,000, two 
above 16,000, two above 17,000, and two above 18.000. 

Four tests of old Douglas fir showed a minimum tensile strength of 
11,414 pounds per square inch, a maximum of 13,954 pounds, and an 
average of 12,663 pounds. 

b. Tensile strength of Canadian red pine. 

Nine tests of red pine showed a minimum tensile strength of 6,274 
pounds per square inch, a maximum of 14,372 pounds, and an average 
of 10,644 pounds. 

c. Tensile strength of Canadian white pine. 

Ten tests of white pine showed a minimum tensile strength of 8,503 
pounds per square inch, a maximum of 14,273 pounds, and an average 
of 11,396 pounds. 

d. Tensile strength of old Canadian spruce. 

Fifteen tests of old Canadian spruce showed a minimum tensile 
strength of 7,662 pounds per square inch, a maximum of 12,792 pounds, 
and an average of 9,763 pounds. 

IV.— SHEARING STRENGTH. 

Great difficulty is encountered in tests for shearing strength to get 
absolutely reliable results. 

The shearing strengths, which are of importance, are the resistances 
along planes tangential and radial to the annular rings. The compound 
shearing strength can be considered as the resultant of the tangential 
and radial shears. 

Professor Bovey states that tho following inferences may be drawn 
from the results of the shearing experiments: — 

"The shearing strength of the timbers is much less near the heart 
(han at a distance from the heart. 

"Generally speaking, the shearing strength increases with the 
weight per cubic foot. 

"The shearing strength increases with the density of the annular 
ring*, or rather with the proportion of hard to soft fibre. 

"A failure sometimes occurs, for which it is difficult to find a com- 
ple t e explanation. 

"As a result of the experiments, the average (breaking) shearing 



602 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

strength of Douglas fir in pounds per square inch is 411, 377, or 403, ac- 
cording as the plane of shear is tangential, at right angles, or oblique to 
the annular rings. 

"In practice, therefore, it will be safe to adopt as the average 
(breaking) co-efficients of shearing strength for Douglas fir, 400 pounds 
per square inch for shears tangential and oblique to the annular rings, 
and 375 pounds per square inch for shears at right angles to the annular 
rings." 

Average breaking shearing strength in pounds, per square inch. 



Kind of Timber. 



New Douglas fir 

O d Douglas fir 

Canadian red pine . . 
Canadian white pine 
Old Canadian spruce 



Tangential 
Shear. 



411 
302 
392 
382 
332 



Radial 
Shear. 



377 

310 



273 

389 



Oblique 
Shear. 



403 
371 
333 
363 

382 



- The number of tests on which above table is based is not very large, 
which fact, combined with the acknowledged difficulty of obtaining ac- 
curate shearing tests, should cause the data presented to be considered 
as approximate only. 

APENDIX N. 

REPORT OF WASHINGTON STATE CHAPTER, AMERICAN IN 
STITUTE OF ARCHITECTS, ON STRENGTH OF STATE OF 
WASHINGTON TIMBERS. 

In the California Architect and Building News, of March, 1895, there 
Is published a report of a special committee of the Washington Stale 
Chapter of the American Institute of Architects on "Authenticated 
Tests of Building Materials of the State of Washington," which gives 
valuable information from actual breaking tests of the transverse 
strength of Washington timbers, the figures given bf-iow indicating the 
calculated ultimate breaking stress in extreme fibre in pounds per 
square inch, based upon the actual breaking load applied at the center 
of the span. 

a. Transverse tests by C. B. Talbot, Civil Engineer, Northern Pao*fi'* 
Railroad. 

Size. 2x4 inches; span, 4 feet. Ultimate extreme fibre stress in pounds 
pel square inch. 

Washington yellow fir, age 1% months to G years; minimum, 0,890 
lbs.; maximum. 9,720 lbs.; average of 5 tests, 7,847 lbs. 

b. Transverse tests by A. J. Hart, M. C, Chicago, Milwaukee and 
St. Paul Railway. 



Sizes, 0x14 inches, 8x16 inches, and 9x16 inches; span, 16 to 20 feet. 
Ultimate extreme fibre stress in pounds per square inch. 

Washington yellow fire, age, 1 day cut; minimum, 6,143 lbs.; maxi- 
mum. 7,982 lbs.: average of 4 tests, 7,323 lbs. 

Ditto, age 6 years; minimum, 5,953 lbs.: maximum, 6,088 lbs.; aver- 
age of 2 tests. 6.020 lbs. 



TIMBER TESTS. 693 

Ditto, used 6 years in a bridge; minimum, 4,138 lbs.; maximum, 5,817 
lbs.; average of 2 tests, 4,978 lbs. 

e. Transverse tests at mills of St. Paul and Tacoma Lumber Com- 
pany, Tacoma, Washington, March, 1890, by A. J. Hart and C. B. Talbot. 

Sizes, 6x14 inches, 8x16 inches, and 9x16 inches; spans, 11 to 17 fee*. 
Ultimate extieme fibre stress in pounds per square inch. 

Washington (Douglas) fir, minimum, 5,263 lbs.; maximum, 7,561 lbs.; 
average of 9 tests, 6,273 lbs. 

Ditto, age 3 years; 1 test, 5,591 lbs. 

Ditto, age 6 years; 1 test, 3,725 lbs. 

Ditto, culled stick; 1 test, 3,544 lbs. 

d. Transverse tests by S. Kedzie Smith, City Engineer, Ballard, 
Washington. 

Sizes, 3x8 inches, 3x12 inches, and 4x12 inches; spans, 8 to 14 feet. 
Ultimate extreme fibre stress in pounds per square inch. Quality of 
lumber a little above the grade of good merchantable lumber, air sea- 
soned for forty days. 

Washington red fir, medium fine grained; 1 test, 6,138 lbs. 

Ditto, coarse grained; minimum, 4,605 lbs.; maximum, 5,700 lbs., 
average of 6 tests, 5,182 lbs. 

Ditto, very coarse grained; 1 test, 4,255 lbs. 

Ditto, grand average of above 8 tests, 5,186 lbs. 

Washington yellow fir, close grained; minimum, 7,500 lbs.; maxi- 
mum, 8,160 lbs.; average of 2 tests, 7,830 lbs. 

e. Comparative transverse tests by C. B. Talbot, Civil Engineer, 
Northern Pacific Railroad. 

Size, 2x4 inches; length, 4 feet; clear span, 3 feet 9 inches; breaking 
load applied at center of span. Ultimate extreme fibre stress in pounds 
per square inch. 

Washington fir, age 3 months; hard, fine grained; actual breaking 
load, 4,320 lbs.; extreme fibre strain, 9,720 lbs. 

Coeur d' Alene (Washington) pine, age 1% months; fine grained; ac- 
tual breaking load, 2,274 lbs.; extreme fibre strain, 5,116 lbs. 

Eastern oak, age 1 year; dry; actual breaking load, 2,428 lbs.; ex- 
treme fibre strain, 5,463 lbs. 

Eastern white pine, age 1 year; dry; actual breaking load, 1,610 
lbs.; extreme fibre strain, 3,622 lbs. 

In other words, the transverse strength of Eastern white pine, East- 
ern oak, Washington pine, and Washinfiton fir, is relatively propor 
tional to 1,610, 2,428, 5,116, and 9,720, or approximately as 1 to iy 2 , to 
3 1-5 to 6. 

f. The following are the averages of all tests for" transverse strength, 
(excepting culls, and old bridge timbers), mentioned in the above com 
mittee report, giving the ultimate breaking extreme fibre stress per 
square inch:— 

Washington yellow fir, 13 tests, 7,402 lbs. 
Douglas fir, 11 tests, 5,979 lbs. 
Washington red fir, 8 tests, 5,186 lbs. 

Grand average of all kinds of Washington or Douglas fir, 32 tests, 
6,359 lbs. 



6g4 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

APPENDIX O. 

MISCELLANEOUS TESTS OF THE NORTHWEST AND PACIFIC 

COAST TIMBERS. 

a. In addition to 10 full-size tests of Washington fir, mentioned 
above (Appendix "N, d"), Mr. S. Kedzie Smith, city engineer, Ballard, 
Wash., made 9 similar tests reported in The Puget Sound Lumberman, 
August, 1894, and February, 1895. The results from these 19 full-size 
tests are, — 

Ultimate extreme fibre stress in pounds per square inch, 3,530 to 
8,160, average 5,420. 

b. Mr. Arthur Brown, superintendent bridges and buildings, South- 
ern Pacific Railroad, established following average ultimate breaking 
stresses as results of tests of Pacific Northwest fir (The Puget Sound 
Lumberman, February, 1894): 

Tensile 15,900 lbs. per square inch 

Crushing 6,000 lbs. per square inch 

Shearing with the grain 600 lbs. per square inch 

Modulus of elasticity 1,272,000 lbs. per square inch 

Transverse (extreme fibre stress) 13,630 lbs. per square inch 

c. The results of about 40 transverse tests of California Spruce and 
Oregon Pine, made by Professor Thurston at the Stevens Institute of 
Technology for the United States Geological Survey in 1880, were as 
follows: 

Average Ultimate Breaking Extreme fibre stress in pounds per 
square inch, for California spruce, 12,228, and for Oregon pine, 11,071. 

Average Ultimate Breaking Compressive stress for short pieces in 
pounds per square inch, for California spruce, 9,200 pounds to 12,800, 
and for Oregon pine, 9,200 to 11,500. 

d. In Engineering News of April 20, 1893, Mr. W. B. Wright, for- 
merly division engineer, M., St. P. & S. Ste. M. Railway, gives infor- 
mation relative to some tests of Oregon pine or Douglas fir from the 
State of Washington made by Mr. George S. Morrison at the Pittsburg 
Testing Laboratory, in 1886. There is a distinction made between red 
and yellow fir. The average co-efficients of ultimate breaking strength 
in pounds per square inch were as follows: 

Compression, Red Fir, 2 tests, 6,099 lbs. 

Yellow Fir, 2 tests, 6,132 lbs. 
Tension, Red Fir, 4 tests, 10,872 lbs. 

Yellow Fir, 5 tests, 11,550 lbs. 
Transverse Strength, Red Fir, 11 tests, 15,894 lbs. 

Yellow Fir, 9 tests, 15,030 lbs. 

e. A few small-size tests of Douglas fir and Oregon Stigar pine were 
made at the machine shops of the Oregon and California Railroad with 
results given below. Specimens for crushing test were 1 inch square 
and 24 inches long: for transverse test, 1 inch square and 12 inches span; 
for tensile test. 1-10 inch by 1 inch. 



TIMBER TESTS. 695 

Ultimate Breaking Strength in Pounds per Square Inch. 



Crushing strength (24 diams.) 

Transverse strength, extreme fiber 
stress 

Tensi e strength 

Sidewise crushing at 1000 lbs. pres- 
sure per square inch 

Shearing strength, 13 tests: 

Least 

Greatest 

Average 



Douglas Fir. 



3,085 

8,658 
16 5 600 

2-100 in. 
indent. 

515 

833 

689 



Oregon Sugar Pine. 



3,391 

8,370 
11,000 

4-100 in. indent. 



APPENDIX P. 



PROFESSOR SOULE'S TESTS OF CALIFORNIA REDWOOD. 

Special Bulletin No. 2, June 1, 1895, University of California, De- 
partment of Civil Engineering, gives the data from tests thus far con- 
ducted on California Redwood in the University laboratory by Mr. 
Frank Soule, professor of civil engineering, as follows: 

Clear, straight-grained, well air-seasoned and dry Humboldt; Red- 
wood (Sequoia Sempervirens). 

Average specific gravity of 126 pieces, .48. 

Average weight per cubic foot, 29.91 pounds. 

Percentage of moisture, average, 15 per cent. 

Ultimate strength. Pounds per square inch. 

Tension, 27 specimens 6,521 

Compression, longitudinal, 31 specimens. * 4,385 

Compression across the fibre, reduction in height of piece of 3 per 

cent., 30 specimens 966 

Compression across the fibre, reduction in height of 15 per cent., 

30 specimens .' 1,197 

Longitudinal shear (pieces clamped to prevent splitting) 8 speci- 
mens 548 

Modulus of rupture, 9 specimens 4,955 

Coefficient (modulus) of elasticity, 8 specimens 797,467 

APPENDIX Q. 

UNITED STATES GOVERNMENT WATERTOWN ARSENAL 
TESTS OF THE SHEARING STRENGTH OF TIMBER WITH 
THE GRAIN RESISTING THE PULLING OUT OF PINS OR 
KEYS. 

Col. T. T. S. Laidley, United States army, made some tests for the 
United States government in 1881, at the AVatertown arsenal on the re- 
sistance offered by timber to the shearing out of round bolts or square 
keys, the force being exerted with the grain of the timber. The bolts 
and square keys were of wrought iron, the bolts 1 inch in diameter, and 
the keys 1 inch and 1% inch. The timber specimens were 2 inches thick 
and thoroughly seasoned. The surface resisting shearing was therefore 
twice the distance of the center of the hole from the end of the stick 



6o6 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

multiplied by the thickness of the stick, which in this case was two 
inches. 

Ultimate Breaking Shearing Stress with the grain in pounds per square 
inch resisting the tearing out of bolts and keys. 



Timber. 



Spruce: 

Round bolt 
Square key. 

White pine: 
Round bolt 
Square key. 

Yellow pine: 
Round bolt 
Square key. 



Center of Hole from End of 




Specimen. 


2 in. 


4 in. 


6 in. 


7 in. 


8 in. 


399 


359 


275 




202 


410 


329 


242 


279 




457 


611 


450 




327 


550 


412 


332 


236 




607 


720 


456 




337 


599 


369 


572 


438 





Average. 



309 
315 



461 
382 



530 
494 



APPENDIX R. 

TRANSVERSE TESTS OF FULL-SIZE OLD AND NEW BRIDGE 
STRINGERS MADE FOR THE CHICAGO, MILWAUKEE AND 
ST. PAUL RAILWAY, UNDER THE DIRECTION OF MR. ON- 
WARD BATES. 



Mr. Onward Bates, engineer and superintendent of bridges and 
buildings, Chicago, Milwaukee and St. Paul Railway, presented a paper 
on "Pine Stringers and Floor Beams for Bridges," to the American So- 
ciety of Civil Engineers (Transactions. November, 1890), in which the 
detail results are given of 67 full-size tests of new and old bridge string- 
ers of white pine, Norway pine, and Douglas fir, made under Mr. Bates'' 
direction. 

Mr. Bates states that the tests lead to the following conclusions: 

"Green timber is not as strong as after it has seasoned." 

"Age and use do not weaken the timber. It preserves its strength 
until weakened by decay." 

"Knots do weaken the timber seriously, both in reducing the effec- 
tive section of the beam, and in causing the fibre to be curly and cross- 
grained." 

"While age does not weaken the timber itself, it weakens it by sea- 
son-checking." 

The paper contains very valuable and pertinent information as to 
the quality and characteristics of bridge timbers of the kinds examined. 
Also a report of Mr. A. J. Hart on Douglas fir. 

The principal average results obtained in the three sets of tests,, 
made respectively at West Milwaukee, Minneapolis, and in the territory 
of Washington, are as follows: 

a. Results from forty full-size transverse tests of bridge stringers 
made at West Milwaukee shops, April, 1889, by Mr. George Gibbs, me- 
chanical engineer, of which 30 stringers were of white pine and 10 
stringers of Norway pine, and of which 14 were new stringers selected 
indiscriminately from accepted stock, and °6 were bridge stringers that 
had been in use from SY 2 to 8y 2 years: 



TIMBER TESTS. 697 

Ultimate breaking extreme fibre stress in pounds per square inch, 
2,350 to 5,376; average, 3,906. 

Modulus of elasticity in pounds per square inch, 712,500 to 1,684,100; 
average, 1,123,090. ' 

The range of results according to the age, kind, and section of stick 
is given in the tables accompanying the paper, and is very instructive. 

b. Results from 14 full-size transverse tests of new white pine bridge 
stringers made at Minneapolis, December, 1889, by Mr. A. J. Hart, dis- 
trict carpenter, of which 7 stringers were from accepted stock, and 7 
stringers from stock that had been rejected by the railroad lumber in- 
spectors. 

Ultimate breaking extreme fibre stress in pounds per square inch: 
Seven accepted sticks, 3,162 to 5,131; average, 4,140. 
Seven rejected sticks, 2,160 to 4,178; average, 3,248. 
Average of all 14 sticks, 2,160 to 5,131; grand average, 3,694. 

c. The results from 12 full-size transverse tests of Douglas fir bridge 
stringers, made by Mr. A. J. Hart, at the mills in the territory of Wash- 
ington, March, 1890, have been mentioned above in Appendix N. Of 
these sticks 9 were new timber, 2 had been in use for 3 years each, and 1 
■**»r 6 years. Mr. Bates sums up the results as follows: 

Ultimate breaking extreme fibre stress in pounds per square inch: 

All 12 tests, 3,597 to 7,544; average, 5,791. 

Omitting a very old and dry stick, that had been in use 6 years, and! 
also a green stick of very poor quality, the results of 10 tests were 5,268 
to 7,544; average, 6,214. 

APPENDIX S. 

COMPARATIVE TRANSVERSE TESTS OF FULL-SIZE OLD AND 
NEW WHITE PINE BRIDGE STRINGERS, MADE BY MR. W. 
H. FINLEY FOR THE CHICAGO AND NORTHWESTERN RA IL- 
WAY. 

Mr. W. H. Finley, engineer of bridges, Chicago and Northwestern 
Railway, published in Engineering News of May 23, 1895, also in The 
Railway Review of June 1, 1895, the detail results of full-size compara- 
tive transverse tests of old and new white-pine bridge stringers, made 
at West Chicago shops, April 18, 1895. 

There were 12 pieces of old stringers from the 85 foot covered Howe 
truss span, erected over the Fond du Lac River, Wisconsin, in 1864. and 
taken down in March, 1895, hence representing timber 31 years in actual 
use. 

Results from the 12 pieces were as follows: 

Ultimate breaking extreme 'fibre stress in pounds per square inch, 
5,139 to 10,616; average, 7,051. 

Modulus of elasticity in pounds per square inch, 715,000 to 1,900,000; 
average, 1,208,250. 

For comparison two 10-inch by 10-inch sticks were selected from the 
stock of new white pine in the railroad company's lumber yard at West 
Chicago. The sticks were well seasoned, and above the average in 
quality. The results were as follows: 

Average ultimate breaking extreme fibre stress in pounds per square 
inch, 5,402; modulus of elasticity in pounds per square inch, 982,500. 

Mr. Finley remarks that these tests confirm the conclusions reached 
by Mr. Onward Bates in the similar tests conducted by him (see Ap- 
pendix R), namely: 

"Green timber is not as strong as after it is seasoned." 



6r.8 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

"Age and use do not weaken the timber. It preserves its strength 
until weakened by decay." 

APPENDIX T. 

TESTS OF DOUGLAS FIR AND CALIFORNIA REDWOOD MADE 
FOR THE SOUTHERN PACIFIC RAILWAY BY MR. JOHN D. 
ISAACS. 



Mr. John D. Isaacs, assistant engineer, Southern Pacific Railway, 
summarizes the results of tests made under his direction as follows: 

"Regarding strength of Oregon pine (properly Douglas fir) and Red- 
wood timber, the following are the averages of many experiments (neg- 
lecting abnormal results) made several years prior to 1895, by our com- 
pany under my supervision." 

Ultimate Breaking Strength in pounds per square inch. 



Tensile 

Crushing , 

Shearing parallel with grain 
Modulus of elasticity 



Douglas Fir. 



15,900 

6,000 

600 

1,272,000 



Redwood. 



8,000 

3,000 

276 

600,000 




Allowable Safe Unit Stresses in pounds per square inch. 
Used in practice under ordinary conditions, by Mr. Isaacs. 



Tensile 

Crushing 

Shearing parallel with grain. . . 
Bearing perpendicular to grain 



"In trestlework red wood is principally used for sills, posts, and 
caps, or wherever the timber is subject to rapid decay, although creo- 
soted fir timber has been replacing red wood for the latter purpose on 
the Southern Pacific Railway system. 

"The tests were made as follows: A large number of logs were cut 
from different portions of trees from various localities and exposures. 
After air-seasoning the logs were cut into 1 inch square pieces; half of 
the pieces from each section were tested by tensile and the other half 
by compressive strain, the pieces being turned down to a round for 
about 8 inches in length. All pieces were tested, except such showing 
sap or splits running across the grain. The diameters were gauged 
very carefully. The machine was a home-made apparatus of about 
25,000 pounds capacity, with a pressure gauge for recording pressures. 
The shearing tests were made by pulling a half-inch round out of some 
of the one-inch pieces. The modulus of elasticity was determined by 
bending <pieces of various dimensions. 

"All of the experimental results have been checked at various times 
by isolated experiments. An extended experience with a great variety 
of timber structures has confirmed my opinion that the units given 
above are just right for good practice. 

''While the testing methods, as compared with more efficient labora- 



TIMBER TESTS. 699 

tory machines, may appear somewhat crude, the results obtained are 
probably just as near the truth, considering the varying characteristics 
of different pieces of the same species of timber." 

APPENDIX U. 

PROFESSOR WING'S FULL-SIZE TRANSVERSE TESTS OF 

DOUGLAS FIR. 

Professor Charles B. Wing, Leland Stanford University, California, 
published in Engineering News of March 14, 1895, an account of the 
methods used and results obtained by him in a series of full-size trans- 
verse tests of Douglas fir. None of the specimens were selected for 
testing. The timber was ordered from a San Francisco lumber yard, 
and would probably rate as a poor lot of "No. 1 Merchantable." The 
sticks contained considerable sap. Some of the sticks failed by shear- 
ing along the fibre parallel to the length of the specimen (see Appendix 
"F — b."). Professor Wing states that it was noted that knots, even 
when sound and tight, weakened the stick by decreasing the section, and 
by causing the fibre to be cross-grained and curly, easily crushing when 
in compression. 

The ultimate breaking extreme fibre stress in pounds per square inch 
obtained from ten sticks, each 6 in. x 10 in. x 17 feet long, was 4,590 to 
7,951, average 6,293. The stick giving the limit of 4,590 was a stick that 
would have been culled in an ordinary lumber inspection. Excluding 
this stick the results ran from 5,580 to 7,951, average 6,482. 

An additional series of ten tests was made with pieces 3 in. x 5 in. 
x 4 ft. 3 in. long, cut from uninjured parts of the large sticks that had 
been previously broken. The results showed ultimate breaking extreme 
fibre stress in pounds per square inch, from 6,438 to 12,056, average 9,- 
257. The stick giving the lowest limit had a knot through the center. 
Excluding this the lowest limit was 7,960. 

APPENDIX V. 

MR. A. L. JOHNSON'S FORMULA FOR TIMBER COLUMNS. 

Mr. A. L. Johnson, civil engineer, in charge of physical tests of U. S. 
Forestry Division under the direction of Prof. J. B. Johnson, of Wash- 
ington University, St. Louis, Mo., with *the consent of Dr. B. E. Fernow, 
chief of forestry division, has kindly contributed the following formula 
for timber columns, which is exceedingly valuable, not only as being 
the latest contribution on the subject, but especially as it is based on 
unpublished actual full-size tests made at Washington University, sup- 
plemented by a critical study and examination of previous full-size col- 
umn tests. 

Mr. Johnson writes on September 13, 1895, as follows: 
The formula was obtained by plotting the tests of full-size beams, 
and is as follows for timber columns with square ends (but not for fixed 
ends): 

700 + 15c 

f = F X 

700 + 15c + c 2 

where f = ultimate breaking unit crushing stress on long column; 
c = ratio of length to least cross-sectional dimension 



(!) 



F = ultimate breaking unit crushing stress on short column. 
Mr. Johnson recommends the following values for F, those for Amer- 



700 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

lean white oak, long-leaf pine, short-leaf pine, white pine, and cypress 
being obtained from recent tests of the U. S. Forestry Division, the 
other values being compiled from the best information available: 

Ultimate Breaking Crushing Stress for short columns in pounds per 

square inch. 

American white oak 4,000 Red cedar 3,500 

Long-leaf pine 5,000 California redwood 3,250 

Short-leaf pine 4,200 Norway pine 3,800 

White pine 3,500 Colorado pine 3,150 

Bald cypress 3,375 Douglas fir 4,400 

Mr. Johnson explains that all long-column formulae, prior to the 
above one presented by him, are based upon the assumption that a 
"square-ended" column is practically a "fixed-ended" column, and hence 
half the length of the column is the length used for the theoretical in- 
vestigations. In reality the so-called square-ended columns in practice 
can hardly be considered as fixed-ended, in spite of the end fastenings, 
and hence the lateral deflection curve under compression will be a true 
continuous curve from one end of the column to the other, and that the 
theoretical deductions should be based upon the full length of the col- 
umn. 

Mr. Johnson considers his formula as of very nearly if not the true 
theoretical form, and the co-efficients are entirely empirical, based upon 
actual tests, hence its superior value to previous column-formulae. 

APPENDIX W. 

MR. A. L. JOHNSON'S RECOMMENDATIONS FOR UNIT VALUES. 

Mr. A. L. Johnson, civil engineer, in charge of physical tests of U. S. 
Forestry Division, under the direction of Prof. J. B. Johnson, of Wash- 
ington University, St. Louis, Mo., with the consent of Dr. B. E. Fernow, 
chief of forestry division, has kindly contributed the accompanying 
table showing the values recommended by him for the ultimate breaking 
unit stress of various kinds of timber. The values for American white 
oak, long-leaf pine, short-leaf pine, white pine, and cypress are obtained 
from results of the tests conducted since 1890 by the U. S. Forestry Di- 
vision, and hence can be considered as authoritative advance informa- 
tion as to the best average values shown by these tests, the test results 
for all the species mentioned, excepting for long-leaf pine, not having 
been published up to the present time. The values for the other species 
given in the table, of which the U. S. Forestry Division has made no 
tests, were compiled by Mr. Johnson from the best test data available, 
making due allowance for the fact that much of the data at hand was 
based on small-size tests. The units given in the table are for large-size 
sticks as used in practice. 

The ultimate crushing strength across grain is taken as the stress, 
producing an indentation of three per cent, of the thickness of the com- 
pressed stick. 



TIMBER TESTS. 



701 



Recommended Values for Unit Stresses of Timber. A. L. Johnson, Oc- 
tober, 1895. Ultimate Breaking Stresses in Pounds Per Square Inch. 







a 


02 

j£2 


a 

© 


CD 
02 

"E 


© 


6* 

oa 




43 






03 . 


a 
•1-1 




T3 

a 


oa 
oa 
O 


© 

a, 


13 






beer 1 




•1— 1 

© •■— 1 


CD 

,a 


§.S 


zn 


a,.q 






a oa 


03 




bo 


,a o« 

+3 oa 


,a 


-4J 02 


Species. 




£ © 
ta a 


c3 


•1— 1 


g a 


be 

a f- 
s © 


-t-3 

bo 


bc^ 

a cd 






«w oa 




oa 0) 

c3 ft 




S a 


a 

CD 


© o< 






O.Q 




© «? 


DO 


<a 02 


■*3 


02 M 






S-9 


02 -ii 

a, 
3 




Crushing 
lbs. per 


Crushing 
grain lb 


oa 
© . 

:a,a 

02 
a a 

(D-pH 

Eh 


b£-* 

.s g 


Long-leaf pine. . 


D 


7,750 


1,440,000 


1.30" 


5,000 


645 


12,000 


500 


Short-leaf pine. . 


D 


6,500 


1,200,000 


1.30 


4,200 


645 


9,000 


400 


White pine 


D 


4,400 


870,000 


1.00 


3,500 


440 


7,000 


300 


Norway pine. .. 




5,450 


1,132,000 




3,800 


430 






Colorado pine . . 




4,900 


888,000 




3,150 


540 






Douglas fir 




6,600 


1,380,000 




4,400 


500 






Redwood 




7,200 


452,000 




3,250 


345 






Red cedar 




5,000 


670,000 




3,500 


750 






Bald cypress — 


D 


5,000 


900,000 


1.10 


3,375 


360 


6,000 


240 




D 


6,000 


1,100,000 


1.25 


4,000 


1,200 


10,000 


800 



Note.— The values marked "D" were obtained from experiments made by the United 
States Forestry Division. The other values were obtained from various sources, chiefly 
from the tenth census report, but so modified as to give results comparable with the 
forestry division values. 

These values are for eighteen per cent, moisture, representing a half dry condition. 
For modifications of these values for other moisture conditions, and for fuller general 
description, see bulletin on "Timber Trestle Design," issued by the forestry division. 



ADDITIONAL DATA. 



As chairman of the committee reporting last year on the subject of 
"Strength of Bridge and Trestle Timbers," I desire to record some addi- 
tional data that have come to my notice since the presentation of that 
report, namely, publications since October, 1895, relating to the strength 
of timber, and a new straight-line column formula, adopted by one of 
our members, Mr. J. E. Greiner, engineer of bridges, B. & O. R. R., as 
also a diagram (Fig. 245) representing the various formulas and results 
of full-size tests for yellow-pine columns. 

In addition, I wish to mention the evident value attributed to this 
report by the technical press and others, not with a view to calling at- 
tention to the personal efforts and work of the members of that com- 
mittee, but purely as an object lesson to this association, and all its 
members, illustrating how we are gradually forcing ourselves to the 
front, and taking the stand that belongs to us by right, in our own par- 
ticular sphere and line of work among the technical, and railroad asso- 
ciations. 

The report was published, mo*re or less in full, by a very large num- 
ber of the leading technical papers of the country, and briefly noticed 
in a number of home and foreign journals. 

The United States government reprinted the report and all the ac- 
companying tables, as an appendix, in a pamphlet on the "Economical 
Designing of Timber Trestle Bridges." 
c The secretary of this association has received numerous requests 



702 AMERICAN RAILWAY BRIDGES AND BUILDINGS, 
from individuals for copies, and, personally, I know that college pro- 
fessors, municipal and railroad engineers, have sent for copies for use 
in their professional work. It has also been utilized, to my own knowl- 
edge, in two of our large cities, where a revision of the building laws 
has been in progress during the last year. 

„ Mr. F. E. Kidder, the well-known architect, of Denver, Colo., and 
author of "Kidder's Pocket Book," has recently published an article on 
the value of uniform and standard unit stresses for timber, for the use 
of engineers and architects, especially with a view to establishing great- 
er uniformity in the building laws of our various cities. After referring 
to the scant data available, consisting mainly of Barlow's "Essay," 
published in 1817; Hatfield's book on "Transverse Strains," published in 
1877, and Trautwine's "Engineer's Pocket Book," Mr. Kidder states as 
follows : 

"The most thorough work that has yet been done in this direction is 
that of the committee on "Strength of Bridge and Trestle Timbers," of 
the Association of Railway Superintendents of Bridges and Buildings, 
as evidenced in its report presented at the fifth annual convention of 
the association, held in New Orleans, October 15 and 16, 1895. 

"This report is a very exhaustive resume of all published tests that 
have been made on American lumber, as well as the recommended 
values of authors and structural engineers. The report fills forty-nine 
closely-printed octavo pages, and contains a great mass of valuable in- 
formation on the subject. 

"As a result of the investigation of this committee, standard unit 
stresses were recommended for all varieties of timber used in bridge 
work at the present day. That these standards will have great weight 
with engineers, and even if necessary, with the courts, cannot be ques- 
tioned. As further evidence of an increased interest in this direction, 
the report of the proceedings of the twenty-ninth annual convention of 
the American Institute of Architects contains two very valuable papers 
on the strength of timber, one by George W. Billiard, of Tacoma, Wash- 
ington, and the other by Prof. J. B. Johnson, of Washington University* 
St. Louis." 

After comparing the units reported by the committee of this associa- 
tion with other recommended values and the units in existing city build- 
ing laws, Mr. Kidder continues: 

"It should be noticed that the values recommended by the railway 
superintendents and individuals agree, in general, very closely. ...» 
It would seem that, with the data now available, standard unit stresses 
might be adopted which would be uniformly recognized throughout the 
country." 

An editorial on the "Working Stresses for Timber Structures," in 
The Engineering Record of November 9, 1895, after a general discussion 
of the question, concludes as follows: 

"In view of the preceding considerations, which fail to pi esent in 
more than outline the actual state of the case, it is a fortunate event 
for the interest of good timber design that a committee of the American 
Association of Railway Superintendents of Bridges and Buildings re- 
ported to their fifth annual meeting at New Orleans, on October 15, last, 
a set of ultimate resistances and working stresses, which may at least 
be considered provisionally justified by such few reliable tests as have 
been made on full-size columns and beams. This set of quantities, 
which we printed in our preceding issue, has great value for all archi- 



TIMBER TESTS. 703 

tects and engineers, and it should be well considered by them in their 
timber designs; and for the most part it would noc be out of place in the 
building laws of all large cities. Many of the quantities given are not 
different from those which well-informed engineers have been using, 
but it is the best succinct statement of empirical constants for timber 
of a complete character which has as yet been put forth." 

Numerous similar notices could be quoted, not only in regard to this 
particular report, but also in connection with other reports presented 
last year, which have been equally favorably criticised and reprinted in 
the technical press, and extensively utilized for practical railroad work. 

The moral of all this is, that we here have direct evidence that the 
work this association has done in the past is bearing fruit, which is a 
most gratifying sign. The aims of this association are not only to 
spread information among our members on the technical subjects we 
are all interested in, but to disseminate such knowledge throughout the 
country, so as not only to make improved methods more generally 
known, but especially so as to standardize the existing practice, and 
thus obtain uniformity, as far as possible, in the various details of our 
work. 

Publications Since October, 1895, Relating to Strength of Timber. 

Bulletin No. 10, IT. S. Department of Agriculture, Division of For- 
estry, entitled "Timber," being a discussion of the characteristics and 
properties of wood. 

Bulletin No. 12, U. S. Department of Agriculture, Division of For- 
estry, entitled "Economical Designing of Timber Trestle Bridges." In 
this pamphlet the report of the committee of the Association of Railway 
Superintendents of Bridges and Buildings on "Strength of Bridge and 
Trestle Timbers" is reprinted, together with the accompanying tables. 

Circular No. 12, U. S. Department of Agriculture, Division of For- 
estry, on the "Mechanical and Physical Properties of Southern Pine," 
published March, 1896, being advance data and summary conclusions 
extracted from a comprehensive bulletin on the subject of "Southern 
Pines," which will be published as soon as the department can do so. 
The department also has in preparation a bulletin on the "Principles 
and Practice of Dry Kilns." 

Mr. William Hood, chief engineer, Southern Pacific Railway, pub- 
lished in Engineering News of June 25th, 1896, extensive data in regard 
to tests of Oregon pine or Douglas fir made under his direction. 

The Department of Civil Engineering of the University of Califor- 
nia, at Berkeley, Cal., has been engaged in extensive tests of Pacific 
coast timbers during the past year. 

The data of all tests of timber made at the Massachusetts Institute 
of Technology, Boston, Mass., have been republished from the Technol- 
ogy Quarterly in a special pamphlet, entitled "Results of Tests Made 
in the Engineering Laboratories of the Massachusetts Institute of Tech- 
nology." Address the secretary of the Society of Arts. 

The results of comparative tests of Washington fir and Eastern 
white oak, made by Mr. O. D. Colvin for the Northern Pacific Railroad, 
were published in Railway Review, issue of March 7th, 1896. 

Notes on white pine timber overloaded in actual use were published 
in Railway Review, issue of March 28, 1896. 

Article of F. E. Kidder on "The Proper Unit Stresses for Timber," 
was published in The Inland Architect, issue of August, 1896. The unit 
values established by the report of the committee of the Association of 
Railway Superintendents of Bridges and Buildings are very favorably 
commented on and compared with the values prescribed by building 



704 AMERICAN RAILWAY BRIDGES AND BUILDINGS. 

laws in Boston, Buffalo, New York, Brooklyn, and Chicago. This arti- 
cle was republished in Railway Review, issue of October 3, 1890. 

Notes on the strength of timber by George W. Bullard, of Tacoma, 
"Washington, and by Prof. J. B. Johnson, of Washington University, St. 
Louis, are included in the proceedings of the twenty-ninth convention 
of the American Institute of Architects held in 1896, at St. Louis. 

Column Formulas for Yellow Pine. 

Since the presentation of the report of the committee on "Strength 
of Bridge and Trestle Timbers" at the New Orleans convention, I have 
had occasion to prepare a diagram showing various formulas for yellow 
pine columns in comparison with actual, full-size tests, which diagram 
was published in the proceedings of the American Society of Civil En- 
gineers. I have prepared a similar diagram, which I present (Fig. 245), 
embodying the data and formulas mentioned in last year's report, in 
addition to the straight-line formula adopted last spring by Mr. J. E. 
Greiner, a member of this association, for the new 1896 issue of the 
General Specifications for Bridges and Buildings, Baltimore and Ohio 
Railroad. 

Mr. Greiner' s formula for yellow pine columns is: 

1 
Breaking weight = 5,000 — 65 — 

d 

For the safe unit stress for columns over seventeen diameters, Mr. 
Greiner specifies as follows: 

1 

Long leaf yellow pine 1,200 — 18 — 

d 
1 

White oak 1,000—15— 

d 
1 

White pine 800—12— 

d 
where 1 = length and d = least thickness, all in inches. 

Mr. Greiner wrote to Mr. Berg as follows in regard to his reasons 
for adopting the above form of formula: 

"I send you herewith a copy of our 1896 specifications, in which you 
will find the several unit stresses on timber which, after a mature con- 
sideration and examination into the results of all tests made up to date, 
I have adopted for our regular practice. If you plot the formula for 
long-leaf yellow pine given in these specifications, on the diagram 
sheet, copy of which you were kind enough to send me, and consider 
that the formula given in my specifications has a factor of safety of 
five, you will observe that the unit of stresses decrease more rapidly as 

1 
the values of — increase than is indicated by the other formulas plotted, 

d 
My reasons are: 

1 There are but few tests having values of — between forty and sixty 

d 

as compared with the number between twenty and forty, and these few 
tests were all more or less selected timber. 



TIMBER TESTS. 



705 




m& Ultimate Breaking 

WeiJ-njt OE Yellow Pine Columns . 

Comparing various formo/ae wi/f> date from fuf/size tests 
Com pi' led 6y ttbffer C. Berg. 

FORMULAE 

J.E.Gre/ner. 

__._ PofWmM.Burr. 

Prof J ft. S fan wood 

PhtEdwardfTB/y. 

C.Sf)d/erSm,Y/>N°/. 

Green harff seasoned 

C Sha/erSm/tf? /Y°S 
Sefecfeaf seasoned sf/cAs 

C.<Sfafer Smith /V<?3. 

for average s//cAs m Serv/ce 

A L. Johns on. 

5.000 pounds unit 6asis 

- -*- -*- A. L Johnson 

7,ooo pounds unit ibasis 

Rill Size Teq ts 

Prof Lanza. 

o/t JSiyaterfowf? straigftgrained. 
20 years seasoned. 

o 3 (J.S.yYaferfotYn-verygreenandtYer 

(/.Sflfaferfo/vn average sticAs 

Poff%?PBurrs averages o/ 
US. Wafer Sown tesfs 

US. fores fry D/y/s/on, Depf 
of Agriculture. 



FIG. 245— DIAGEAM FOR ULTIMATE BREAKING WEIGHT OF YELLOW 

PINE COLUMNS. 



7o6 AMERICAN RAILWAY BRIDGES AND JBUILDINGS. 

2. Timber when used in ordinary service, is almost invariably fresh 
and unseasoned and, owing to the exposure to the rays of the sun, It Is 

1 

more apt to warp or bend when the values of — are greater than forty, 

d 

than when these values are less than forty. 

3. The longer the stick, the greater number of defects it is likely to 
have. 

4. As 1,200 pounds on the extreme fibres is generally recognized as 
about the right thing for either tension or compression in beams, I con- 
sider it advisable to use this same 1,200 pounds as a basis of the column 
formula. 

5. A straight line formula will represent the plotted values of all 
tests made, just as well as any possible curve will do it, and it is more 
readily applied. 

I hesitated a long time before adopting a formula differing from 
those already proposed by engineers of recognized standing, but so 
long as no two of them agree and one more formula will cut no figure, 
I preferred to add one more, which in my judgment will fulfill practical 
purposes and is just as good as the others proposed." 

An examination of the diagram (Fig. 245) would seem to indicate 
that a straight-line formula will give as good practical service as a com- 
plicated one, and that Mr. Greiner's formula offers a simple, safe and 
conservative rule for proportioning timber columns. 

WALTER G. BERG. 













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